Tech Glossary
Plain-English definitions for every technical term you'll encounter across our guides. No jargon, no assumptions — just clear explanations with links to guides that use each concept.
A
A command-line tool that lets a computer communicate with an Android device over USB or Wi-Fi. Used by developers for testing and by tools like scrcpy for screen mirroring. Requires enabling "USB Debugging" in Android's Developer Options. It's powerful — treat it like admin access to your phone. See: scrcpy Guide
Everything an attacker could possibly use to get in: open network ports, running services, user accounts, installed software, connected devices, and the people who use them. A smaller attack surface means fewer ways in. Every service you switch off, every port you close, and every unused account you delete shrinks it. This is why "turn off what you don't use" is the single most cost-effective security advice there is. See: Router Security Guide
An AI system that can use tools, make decisions, and take multiple steps autonomously to complete a task — unlike a standard chatbot that just responds to one prompt. Agents can search the web, read files, run code, and interact with APIs. They loop: think → act → observe → think again. Examples include coding agents (Claude Code), research agents, and automation agents. Because agents can take real actions (delete files, send emails), they should always be reviewed before granting access to sensitive systems. See: AI Agents Guide
A way for one piece of software to talk to another. When you use an AI chatbot, your message is sent to the AI company's API, which processes it and sends a response back. APIs are how different services communicate without humans in the middle. See: API Keys & .env Guide
A password-like string that proves you're allowed to use a service's API. Like a valet key for your account — it grants specific permissions without giving full access. Secret keys start with sk- and must be kept private. Publishable keys start with pk- and are safe to share. See: API Keys & .env Guide
Short for "application" — a program that does a specific job. Your web browser is an app. So is your email client, your password manager, and your weather widget. "App" usually means something you install (on a phone or computer); "web app" means something you use in a browser without installing.
Proving you are who you say you are. Passwords are the most common form of authentication. Two-factor authentication (2FA) adds a second proof — usually a code from your phone. "Auth" is shorthand you'll see everywhere (OAuth, auth tokens, auth keys).
B
When a company you have an account with loses control of its data, and your email address, password or personal details end up in the hands of criminals. You are not at fault, but you are affected. The real danger is not the breach itself but password reuse: if you used that same password elsewhere, it now works on those accounts too. Response: change the password everywhere you reused it, and turn on two-factor authentication. Check whether you appear in a known breach at haveibeenpwned.com. See: Password Manager Guide
A scam aimed at businesses where the attacker impersonates a supplier, a customer or a colleague to get money paid or data shared. A common version: an email that looks like it comes from a known supplier, saying their bank details have changed. The defence is not spotting a fake email, it is a rule that bank detail changes are always confirmed by phone, using a number you already had. See: Spot AI Scams Guide
A copy of your data stored somewhere safe. If your computer dies, gets stolen, or gets hit by ransomware, a backup means you don't lose everything. The rule of thumb is 3-2-1: three copies, on two different types of storage, one off-site. See: Backups Guide
How much data can travel through your internet connection at once. Think of it like a pipe: more bandwidth = wider pipe = more water can flow at once. Streaming video uses lots of bandwidth; sending an email uses almost none.
The most common command-line shell — the program that interprets what you type into a terminal. Default on Linux and Mac, and available on Windows via WSL. When a guide says "run this in bash," it means "open your terminal." See: Command Line Guide
Information represented using only two values: 0 and 1. All digital data — text, images, video, programs — is ultimately stored as binary. When you see "download the binary," it means a ready-to-run program file (as opposed to source code that must be built first).
A list of websites, IP addresses, or domains that are deliberately blocked. Used by ad-blockers like Pi-hole and NextDNS. Opposite of allowlist.
Starting up a computer (boot) or restarting it (reboot). Booting loads the operating system from storage into memory. Rebooting clears temporary problems and applies updates. "Have you tried turning it off and on again?" is rebooting — and it genuinely fixes a surprising number of issues.
The program you're using right now to read this page. Chrome, Firefox, Edge, Safari, and Brave are all browsers. They take code from the internet (HTML, CSS, JavaScript) and turn it into readable pages with buttons, images, and text. Your browser is the most important piece of software on your computer from a privacy perspective. See: Mullvad Browser Guide
The basic unit of digital information. One byte stores roughly one character of text. Kilobytes (KB) = thousands, Megabytes (MB) = millions, Gigabytes (GB) = billions, Terabytes (TB) = trillions. A photo is a few MB. A movie is a few GB. Your phone probably has 64–256 GB of storage.
C
A network of servers spread around the world that cache your website's content closer to visitors. Makes sites load faster and handles traffic spikes. Cloudflare is the most popular CDN. See: Cloudflare Guide
A modern web server and reverse proxy written in Go. Its standout feature: automatic HTTPS. Caddy obtains and renews TLS certificates from Let's Encrypt with zero configuration — you don't even need to think about it. Its configuration format (the Caddyfile) is dramatically simpler than Nginx or Apache configs. If you're self-hosting services behind a domain, Caddy is the easiest way to give each one HTTPS. See: Caddy Guide
A free, open-source home cloud OS that gives you an app-store-like web dashboard for managing Docker containers. Install it on a Linux machine with one command, then browse and install apps (Jellyfin, Pi-hole, Nextcloud, and 100+ more) with a single click. Includes a built-in file manager and system monitoring. Perfect for people who want the power of Docker without the command line. See: CasaOS Guide
Another name for the terminal. A text-based way to interact with a computer by typing commands. See: Command Line Guide
The device or program that requests something from a server. When you open a website, your browser (the client) asks the website's server for the page. Email clients (Thunderbird) ask email servers for your messages. In tech, "client" almost always means "the one making the request."
"Someone else's computer." When you use a cloud service, your data and processing happen on servers owned by Amazon, Google, Microsoft, or another provider — not on your local machine.
In Git, a saved snapshot of your work. Each commit has a message explaining what changed and why. Think of commits like save points in a video game — you can always go back to any previous one. See: Git & GitHub Guide
A lightweight, isolated package that contains everything an application needs to run — code, libraries, settings. Containers don't interfere with each other or with your main operating system. Docker is the tool that manages them. See: Docker Guide
A small file a website stores in your browser to remember things — login status, preferences, shopping cart contents. Tracking cookies follow you across sites for advertising. Privacy-focused analytics (Plausible, Umami) don't use cookies. See: Self-Hosted Analytics Guide
The "brain" of your computer — the chip that does the actual computing. Everything your computer does goes through the CPU. Modern CPUs have multiple "cores" (think: multiple mini-brains) that can work on different tasks simultaneously. See also: GPU.
Making files smaller so they take up less space and transfer faster. ZIP files are compressed folders. Images use compression (JPEG, PNG) to reduce file size. Some compression is "lossless" (no quality lost — like ZIP), some is "lossy" (some detail sacrificed for smaller size — like JPEG).
Taking one piece of content and adapting it for different platforms and formats. For example, turning a blog post into five tweets, a LinkedIn post, and a newsletter. AI excels at this — it can rephrase, shorten, and reformat while keeping your core message intact. A major time-saver for small business marketing. See: AI for Marketing Guide
A scheduled task that runs automatically at a set time — daily backups, weekly reports, hourly health checks. Named after "cron," the Linux scheduler. "I'll set up a cron job for that" means "I'll make this happen automatically on a schedule."
The language that controls how web pages look — colours, fonts, spacing, layouts. HTML provides the content (headings, paragraphs); CSS makes it look good. Every website you've ever visited uses CSS. The dark theme, gold accents, and card layouts on this site are all CSS.
Using AI to review CVs and resumes against a job description — comparing skills, experience, and qualifications. AI can score candidates and flag gaps, but should assist human decisions, not replace them. Paste CVs into an AI tool with the job spec and ask for a comparison table. Important: never upload CVs containing personal data to public AI tools without the candidate's consent. See: AI for HR Guide
D
Everything about you that is publicly visible online: your name, photos, phone number, old forum posts, staff listings, and the details of any company you own. Anyone targeting you starts here, reading what you already published rather than breaking in. The point of looking at your own footprint is not to vanish, it is to know what is visible and choose it deliberately. See: Digital Footprint Guide
Organised storage for information. Think of it as a super-powered spreadsheet that software can read and write to instantly. When you log into a website, your username and (encrypted) password are looked up in a database. Common databases: SQLite, PostgreSQL, MySQL.
A program that runs in the background, waiting to do its job — like a butler who stands quietly until you ring the bell. Web servers, databases, and scheduled task runners are all daemons. You don't interact with them directly; they just work silently. On Windows, these are called "services." Pronounced "demon."
AI-generated or AI-manipulated media — a video where someone's face is swapped, a cloned voice speaking words they never said, or a photorealistic image of something that never happened. See: AI Safety Guide
Putting software into production — making it live and available to real users. When you "deploy a website," you're moving it from your computer to a server where the public can access it. Deployments can be manual (copying files) or automated (push to git, it goes live).
The system that automatically assigns IP addresses to devices on your network. When your phone joins Wi-Fi, DHCP gives it an address so it can talk to the internet. Without DHCP, you'd have to manually configure every device — which is why it's on by default in every router.
A version of Linux packaged with specific software and defaults. Ubuntu, Linux Mint, Fedora, and Debian are all Linux distributions. They share the same core (the Linux kernel) but have different looks, package managers, and philosophies. "Distro" is just shorthand. See: Linux Migration Guide
A file whose name starts with a dot — like .env or .gitignore. On Linux and Mac, dotfiles are hidden by default (they're configuration files, not documents). On Windows, hidden files work differently but serve the same purpose. The .env file that stores your API keys is a dotfile.
The internet's phonebook. When you type starcaller.uk, DNS translates that name into the IP address where the website actually lives. DNS filtering (Pi-hole, NextDNS) blocks requests to known ad/tracker/malware domains before they even load. See: Pi-hole Guide and NextDNS Guide
A tool that runs applications in containers — isolated environments that don't conflict with each other or your system. Most self-hosted apps (Nextcloud, Jellyfin, Pi-hole) are distributed as Docker containers. See: Docker Guide
A way to define and run multi-container applications with a single configuration file (docker-compose.yml). Instead of starting each container individually, you run one command and everything starts together. See: Docker Guide
E
Hidden information stored inside a photo file by the camera that took it. It often includes the exact GPS location, the date and time, and which device was used. This is the most common accidental leak: posting a photo of a new purchase, a pet, or a school run can reveal exactly where you live. Turn off location tagging in your phone's camera settings, and strip location before posting publicly. See: Digital Footprint Guide
Scrambling data so only someone with the right key can read it. End-to-end encryption means the service provider can't read your data either — only you and the recipient. See: Encryption Guide
A key-value pair stored outside your code that holds configuration or secrets. The .env file is the standard place to keep API keys, database passwords, and other sensitive values that should never be committed to git. See: API Keys & .env Guide
F
A technique websites use to identify you based on your browser's unique configuration — screen size, installed fonts, timezone, language, and dozens of other details that together form a unique "fingerprint." Unlike cookies, fingerprints are hard to block. Mullvad Browser resists fingerprinting by making all users look identical. See: Mullvad Browser Guide
A filter that controls which network traffic is allowed in or out of a computer or network. Can be hardware (router) or software (Windows Defender Firewall). Blocks unauthorised access while allowing legitimate traffic.
The most advanced and typically largest AI models at any given moment — the ones pushing the boundaries of capability. Frontier models (like GLM-5.2, Kimi K3, Fable 5, GPT-4o, Claude 3.5) usually require datacentre-grade hardware to run, often have hundreds of billions of parameters, and may not release their model weights publicly. They set the benchmark that smaller, consumer-runnable models are measured against. See: Local AI Models Guide
Software whose source code is publicly available for anyone to inspect, modify, and share. Free as in freedom, not necessarily free as in zero cost (though most FOSS is also free of charge). Examples: Linux, Firefox, RustDesk, Thunderbird.
G
European privacy law that gives individuals control over their personal data. Requires consent before collecting data, the right to access and delete your data, and heavy fines for violations. Self-hosted and cookieless analytics tools (Plausible, Umami) are GDPR-compliant by default. See: Self-Hosted Analytics Guide
The practice of optimizing content so AI systems — ChatGPT, Claude, Perplexity, Google AI Overviews — cite or recommend it. Unlike SEO (ranking in search results), GEO is binary: you're either in the AI's answer or you're not. Key tactics include citing sources, using declarative headings, and including verifiable statistics. See: SEO & GEO Guide
A version control system that tracks changes to files over time. Lets you see who changed what and when, revert to previous versions, and collaborate without overwriting each other's work. GitHub is a website that hosts git repositories. See: Git & GitHub Guide
A website that hosts git repositories online — think of it as Google Drive for code. It adds collaboration tools (pull requests, issues, discussions) on top of git. Owned by Microsoft. Most open-source projects live on GitHub. See: Git & GitHub Guide
A specialised processor originally designed for graphics, now essential for AI. GPUs can do thousands of calculations simultaneously, making them dramatically faster than CPUs for training and running AI models. See: Ollama Guide
What you're using right now — a visual interface with buttons, icons, menus, and windows. The opposite of a CLI (command line). Most software has both: a GUI for everyday use, a CLI for automation and power users.
H
A deliberate decoy set up to attract attackers and warn you they are there. On a network it might be a fake server that looks interesting but serves no real purpose — anything touching it is suspicious by definition, because nothing legitimate should. A simple version for a small business: an unused account or a file that should never be opened. Useful as an early-warning tripwire, not as a barrier. See: Router Security Guide
The standard language for creating web pages. HTML uses tags (like h1 for headings and p for paragraphs) to structure content. Every website you visit is built with HTML. CSS styles it; JavaScript makes it interactive.
The protocol web browsers use to fetch websites. HTTPS is the encrypted version — it prevents anyone between you and the website from seeing what pages you're visiting or stealing your passwords. The padlock icon in your browser bar means HTTPS is active.
The central hub for open-source AI — think of it as GitHub for machine learning models. Hosts over 1 million models (LLMs, image generators, speech recognition, embeddings), 200,000+ datasets, and interactive demos called Spaces. Researchers and companies publish their models here; you can browse, download, and use them for free. The Hugging Face Hub is where you go to find models that run locally with Ollama. See: Hugging Face Guide
I
What you do in the first hours after a suspected hack. The counter-intuitive rule is to disconnect from the network but not shut the machine down: disconnecting stops data leaving, while shutting down destroys evidence held in memory. Then write a timeline of what you saw while you still remember it, and call your bank or insurer in that order if money is involved. See: After a Cyber Incident Guide
A program for writing code — like a word processor, but for software. VS Code is the most popular IDE. IDEs provide syntax highlighting (colours that make code readable), autocomplete, error checking, and a built-in terminal. You can write code in Notepad, but an IDE is like upgrading from a screwdriver to a power drill.
A unique number that identifies a device on the internet, like a postal address for your computer. Public IPs are visible to the world; private IPs (192.168.x.x) are only visible on your local network.
The company you pay for internet access — BT, Virgin, TalkTalk, Sky, Comcast, etc. Your ISP can see which websites you visit (unless you use a VPN). They assign your public IP address, which changes periodically unless you pay for a static one.
J
The programming language that makes websites interactive — buttons that do things, forms that validate, pages that update without reloading. Almost every website uses it. Despite the name, it has nothing to do with Java. If you're learning to code, JavaScript is one of the most practical starting points.
A lightweight format for storing and exchanging data. Looks like a structured shopping list with curly brackets and colons. APIs almost always return data as JSON. It's human-readable (unlike binary) and every programming language can parse it. You'll see .json files everywhere.
K
The core of an operating system — the part that talks directly to the hardware. Linux is technically just a kernel; the full operating system (Ubuntu, Android) is the kernel plus all the software around it. You'll rarely interact with the kernel directly, but it's the reason your computer works at all.
L
Giving every person, program, and AI agent the smallest amount of access it needs to do its job, and nothing more. If a tool only needs to read a folder, don't give it permission to write to it. If an AI agent only handles email, don't let it near your bank. The point is limiting the damage when something goes wrong: with least privilege, a compromised account or tricked agent can only reach what it was already allowed to. This is the single most effective control for AI agents, because you cannot stop an agent being tricked but you can stop it being able to do much. See: Securing AI Agents
A free, open-source operating system that powers most of the internet's servers, all Android phones, and increasingly desktop computers. Unlike Windows or macOS, Linux comes in many versions (called distributions or "distros") — Ubuntu and Linux Mint are the most beginner-friendly. See: Linux Migration Guide
The technology behind ChatGPT, Claude, and other AI chatbots. An LLM is a neural network trained on enormous amounts of text that learns to predict what word comes next. The result is a model that can write, summarise, translate, and reason — though it doesn't truly "understand" anything the way a human does. See: AI Comparison Guide
The number of "weights" in an AI model — roughly, how many numbers it uses to make decisions. Measured in billions: 3B (small, fast, runs on a phone), 7B (balanced, runs on most laptops), 13B (more capable, needs 16GB+ RAM), 70B (very capable, needs a powerful GPU). Larger models are generally smarter but slower and need more memory. When choosing a local model, match the parameter count to your hardware. See: Local AI Models Guide
Running on your own hardware, not someone else's server. Local AI (via Ollama) means your prompts never leave your machine. Local storage (Nextcloud on your own server) means you control the hard drive. Opposite of cloud-based.
A special address (127.0.0.1 or localhost) that always points to your own computer. When a guide says "visit http://localhost:8080," it means "open this on the machine you're working on." It only works from the same computer — nobody else can access it unless you explicitly expose the port.
A file that records what a program is doing — errors, warnings, successful operations, who logged in and when. When something breaks, "check the logs" is the first debugging step. Logs are your software's diary: they won't prevent problems, but they'll tell you what happened.
M
Short for "malicious software" — programs designed to harm your computer, steal your data, or hold your files for ransom. Viruses, trojans, spyware, and ransomware are all types of malware. Good security habits (updates, backups, not clicking suspicious links) are your best defence.
A simple way to format text using plain-text symbols. Typing **bold** makes bold, # Heading makes a heading. Used everywhere — README files, forums, note-taking apps, and chat platforms. Files end in .md. Much simpler than HTML; if you can type a text message, you can write Markdown.
Using software (and increasingly AI) to handle repetitive marketing tasks automatically — scheduling social media posts, sending email sequences, generating ad copy variants. AI tools can now draft, personalise, and A/B test marketing content at scale, but human review is essential for brand voice and accuracy. See: AI for Marketing Guide
An AI architecture where the model is split into multiple smaller "expert" sub-networks, and each query only activates a few of them. This means the total model might have hundreds of billions of parameters, but only a fraction are used for any given input — making MoE models more efficient than dense models of equivalent capability. Mixtral 8x7B and DeepSeek V3 are well-known MoE models. The trade-off: the full model still needs enough total RAM to hold all experts, even if only some are active. See: Local AI Models Guide
The trained neural network that powers an AI system. Think of it as the "brain" — different models have different strengths. DeepSeek V4 excels at reasoning, Claude at writing, GPT-4o at general tasks. Models range from tiny (runs on a phone) to enormous (requires a datacentre). See: AI Comparison Guide and Ollama Guide
N
The technology that lets all your home devices share one public IP address. Your router does NAT: it gives each device a private address (192.168.x.x) and translates between those and the single public address your ISP assigned. This is why you can have 20 devices on Wi-Fi but the outside world only sees one.
Two or more devices connected so they can share information. Your home Wi-Fi is a network. The internet is just a network of networks. When someone says "check your network," they usually mean "check your internet connection."
A JavaScript runtime — it lets you run JavaScript outside a browser, on a server or your own machine. Many modern web tools (npm, Vite, Next.js) are built on Node. If a guide says "install Node," it means install Node.js so you can run JavaScript-based tools from the command line.
O
Confirming an important request through a separate channel you already trust, rather than the one the request arrived on. If an email asks you to change bank details, you phone the number you already had on file, not the number in the email. This single habit defeats most impersonation, phishing and AI voice-cloning attempts, because it does not depend on spotting the fake. See: Spot AI Scams Guide
A free note-taking app that works on plain Markdown files stored on your computer. Notes can be linked together with [[wiki-style links]], creating a web of interconnected ideas. Your data stays local — no cloud required. Popular for building "second brains," personal knowledge management, and research note-taking. See: Obsidian Guide
The process of getting a new employee or customer set up with the tools, accounts, and information they need. AI can automate large parts of it: generating welcome emails, creating first-week schedules, producing IT setup checklists, and writing digest versions of employee handbooks. Upload your existing onboarding materials to an AI tool and ask it to create structured onboarding documents. See: AI for HR Guide
Software whose source code is publicly available. Anyone can inspect it for security issues, verify it does what it claims, modify it for their own needs, or contribute improvements. Open source doesn't always mean free of charge, but most open-source projects are free. Examples: RustDesk, Linux, Firefox, Ollama, Pi-hole.
The master program that manages everything on your computer — Windows, macOS, Linux, Android, iOS. The OS handles the keyboard, screen, files, and running apps. When you "install an OS," you're setting up the foundation that all your other software runs on top of. See: Linux Migration Guide
P
A tool that installs, updates, and removes software from one place. Instead of downloading installers from websites, you run one command. Linux has apt (Debian/Ubuntu) and dnf (Fedora). Mac has Homebrew. Python has pip. Package managers handle dependencies automatically so you don't have to chase down which libraries something needs.
A password-less login method that uses your device's unlock mechanism (fingerprint, face, PIN) instead of a typed password. More secure than passwords because there's nothing to steal, phish, or forget. Supported by Google, Apple, Microsoft, and increasingly every major website. The successor to passwords.
A way of tricking an AI by hiding instructions in text it reads. The AI can't reliably tell the difference between your instructions and text it picks up from elsewhere, so a web page, email or document containing hidden commands may be followed as if you wrote them. Direct injection is typed by a user. Indirect injection hides in content the AI reads on your behalf — the dangerous kind, because you never see it. There is no reliable fix today; the defence is limiting what the AI can reach. See: Securing AI Agents
An app that generates, stores, and auto-fills strong, unique passwords for every account. You only need to remember one master password. Without one, most people reuse passwords — which means one breached site compromises everything. See: Password Manager Guide
Remote desktop access that survives disconnection — a permanent password lets someone reconnect anytime, even when you're not at the computer. Appropriate for your own machines; never appropriate for a client or support session. See: Remote Support Safety Guide
A scam where someone pretends to be a trusted organisation (your bank, Amazon, IT support) to trick you into revealing passwords or installing malware. Usually arrives via email or text. The golden rule: never click a link in an unexpected message asking for credentials. Go to the website directly instead. See our guides on password managers and router security for protection strategies.
A numbered channel that a specific service listens on. Web servers use port 80 (HTTP) and 443 (HTTPS). Email uses port 25 (SMTP). When a Docker command says -p 8080:80, it means "map port 8080 on the host to port 80 in the container." See: Docker Guide
The text you type into an AI chatbot. A well-structured prompt produces better results. System prompts set the AI's behaviour and tone for an entire conversation. See: System Prompt Guide
A web-based management interface for Docker. Instead of typing docker commands in a terminal, you get a visual dashboard showing containers, images, volumes, and networks. Includes one-click app templates, a docker-compose stack editor, multi-server management, and resource monitoring. Portainer Community Edition is free and open-source. See: Portainer Guide
Text with no formatting — no bold, no colours, no fonts. What you see in a terminal or Notepad. The opposite of rich text (Word documents, web pages). Plain text is universal: every computer can read it, it's small, it's searchable, and it'll still be readable in 50 years. Code, config files, and .env files are all plain text.
A set of instructions that tells a computer what to do. Apps, software, programs — they mean the same thing. A web browser is a program. The calculator on your phone is a program. Your operating system is a collection of programs working together. "Program" is the most general term; "app" is casual; "software" is the broad category.
A pair of mathematically linked codes used in encryption. The public key can be shared with anyone (like your email address); the private key must be kept secret (like your password). SSH and TLS/SSL both use key pairs. This is the foundation of secure communication on the internet.
Q
A request for information. When you type something into a search engine, that's a query. When an app asks a database "give me all orders from last week," that's a query. When you send a message to an AI chatbot, that's also a query. One word, many contexts — but it always means "asking for something."
A technique that compresses AI models by reducing the precision of their internal numbers — from 16-bit floats to 4-bit integers, for example. This dramatically reduces memory usage (a 7B model goes from ~14 GB to ~4 GB) with minimal quality loss. Ollama uses 4-bit quantisation by default, which is why you can run models that would otherwise need much more RAM. The trade-off is tiny — most users won't notice the difference between a quantised and full-precision model. See: Local AI Models Guide
R
Your computer's short-term memory. RAM holds what you're working on right now — open apps, browser tabs, unsaved documents. It's fast but temporary: everything in RAM disappears when you turn off the power. More RAM = more things you can do at once without slowing down. 8GB is minimum these days; 16GB is comfortable. Saving a file moves it from RAM to permanent storage (your hard drive or SSD).
A type of malware that encrypts your files and demands payment to unlock them. The single best defence is having backups that aren't connected to your computer (offline or cloud). If you have backups, ransomware is an inconvenience. If you don't, it's a catastrophe. See: Backups Guide
A folder that git is tracking — usually a project with all its files and history. GitHub hosts repositories online. "Repo" is shorthand. "Clone the repo" means download a copy. "Push to the repo" means upload your changes. See: Git & GitHub Guide
A server that sits between the internet and your applications, routing requests to the right place and handling SSL encryption. Caddy is the simplest modern reverse proxy (automatic HTTPS with zero config). Nginx and Traefik are other popular options. Cloudflare's orange-cloud proxy is a cloud-based reverse proxy. See: Caddy Guide and Cloudflare Guide
The box that connects your home network to the internet. It directs traffic between your devices and the outside world, assigns local IP addresses, and usually provides Wi-Fi. Your ISP typically gives you one; you can also buy your own. Securing your router is one of the most important things you can do for home network security. See: Router Security Guide
S
A computer that provides services to other computers. When you visit a website, a server somewhere sends you the page. A server can be a massive machine in a datacentre or a Raspberry Pi in your cupboard — the key thing is that it's always on and waiting for requests. "The server is down" means the computer that was supposed to respond isn't responding.
AI tools staff use at work without telling anyone or getting approval. It is almost never malicious — someone finds an AI assistant saves them an hour a day and simply starts using it. The risk is that confidential data (customer lists, contracts, payment details) gets pasted into consumer tools that may train on it. A discovered tool is a manageable one; a hidden tool is not. The fix is a short approved-tools policy, not a ban. See: Shadow AI Guide
Tricking a person rather than hacking a computer. Instead of finding a software flaw, the attacker phones up, emails, or walks in and persuades someone to hand over access or information. AI has made this far more convincing: fluent, error-free writing and cloned voices are now cheap. The old advice to "look for bad spelling" no longer works. The reliable defence is verifying anything important through a separate, known channel. See: Email Security Guide
A free, open-source tool that mirrors and lets you control an Android phone from a computer over USB or Wi-Fi. No app installation needed on the phone — it uses Android's built-in developer bridge (ADB). Fast (30-120 fps), lightweight, and works on Windows, Mac, and Linux. See: scrcpy Guide
A period of interaction between you and a service — from when you log in until you log out (or the connection times out). Your current browser session is what keeps you logged into websites without re-entering your password on every page. "Session-based access" means access lasts only for one interaction and then expires. See: Remote Support Safety Guide
Running services on your own hardware instead of paying someone else to run them. Self-hosted cloud storage (Nextcloud) vs Google Drive. Self-hosted media (Jellyfin) vs Netflix. Self-hosted AI (Ollama) vs ChatGPT. You control the data and there's no monthly subscription — but you're responsible for maintenance, backups, and security.
Remote desktop access that uses a one-time code — once disconnected, that code never works again. Every StarCaller Academy remote support session uses this model. The safer alternative to persistent access. See: Remote Support Safety Guide
When attackers compromise something you trust, rather than attacking you directly. Instead of breaking into your computer, they tamper with a piece of software, a model download, or an update that your computer installs willingly. It is effective because you are the one letting it in. Notable examples include compromised software updates and poisoned packages on public code repositories. The practical defence is to download from official sources, prefer signed releases, and know what you have installed. See: Hugging Face Guide
The program that sits between you and the operating system, interpreting commands you type. Bash is the most common shell. Zsh (Mac default) and PowerShell (Windows) are others. They all do the same thing — the syntax just differs slightly. See: Command Line Guide
The protocol that sends email from one server to another. Every email you send travels via SMTP. When you configure an email client (Thunderbird, Outlook), you provide an SMTP server for outgoing mail. The standard port is 25, but secure alternatives use 465 (SSL) or 587 (STARTTLS). Without proper authentication (SPF, DKIM, DMARC), anyone can spoof emails from your domain. See: Email Security Guide and Email Privacy Guide
Planning and automating social media posts in advance. AI tools can help draft post copy, suggest hashtags, and adapt content for different platforms (LinkedIn vs Twitter vs Instagram). The key is maintaining your authentic voice — always give the AI examples of your best posts first so it learns your style. See: AI for Marketing Guide
The programs that run on your computer — everything from your operating system to your web browser to the calculator app. Software is the instructions; hardware is the physical machine that runs them. You can't touch software, but you use it every second your computer is on.
A shortcut that points to another file or folder. Like a desktop shortcut, but at the filesystem level — programs see it as the real thing. Used to keep files in one place while making them appear in another. If you delete a symlink, the original file is untouched.
The human-readable instructions that make up a program, before being turned into something the computer can run. It's the recipe, not the cooked meal. Open-source software makes its source code public. When someone says "read the source," they mean look at the original code to understand what the program really does.
Encryption protocols that secure connections between your browser and websites. TLS is the modern version of SSL (the terms are used interchangeably). Provides the padlock icon and "https://" in your browser. Cloudflare can handle SSL for sites behind it. See: Cloudflare Guide
A way to securely connect to and control a remote computer via the command line. Used to manage servers, Raspberry Pis, and cloud instances. Traffic is encrypted end-to-end.
Modern computer storage with no moving parts — much faster than traditional hard drives (HDDs). If your computer boots in seconds, it has an SSD. Ideal for operating systems and frequently-used programs. Use HDDs for bulk storage (media, backups) where speed matters less. The single biggest upgrade you can give an older computer.
The practice of improving a website so it ranks higher in search engine results (Google, Bing). Involves writing quality content, using descriptive titles and headings, earning links from other sites, and ensuring technical factors like page speed and mobile-friendliness are solid. Distinct from GEO, which optimizes for AI citations. See: SEO & GEO Guide
T
A mesh VPN that creates a private network between your devices, no matter where they are physically. Think of it as running an invisible ethernet cable between your laptop, your home server, and your phone — they can all talk to each other securely, even when you're on café Wi-Fi. See: Tailscale Guide
The text-based interface to your computer. Also called command line, console, or shell. A window where you type commands and see text output. See: Command Line Guide
A second layer of security beyond a password. After entering your password, you also provide a code from your phone or a physical key. Even if someone steals your password, they can't log in without the second factor. Strongly recommended for email, banking, and any account that matters.
U
Sending a file from your device to the internet. Posting a photo to social media, attaching a document to an email, backing up files to the cloud — all uploads. Upload speeds are usually slower than download speeds on home internet connections. Opposite of download.
A web address — the thing you type into your browser's address bar. https://starcaller.uk/how-to is a URL. It has three parts: the protocol (https://), the domain (starcaller.uk), and the path (/how-to). People use "URL" and "link" and "web address" interchangeably.
V
A computer simulated entirely in software. You can run Windows inside a VM on a Mac, or Linux inside a VM on Windows — the guest OS thinks it has a real computer to itself. VMs are sandboxed: anything that happens inside stays inside. They're used for testing, running incompatible software, and isolating risky applications. WSL is Microsoft's streamlined VM for running Linux on Windows.
Encrypts your internet traffic and routes it through a server in another location. Hides your IP address from the websites you visit and your internet provider. Tailscale is a mesh VPN that connects your own devices — think of it as a private network that works anywhere. See: Tailscale Guide
An isolated Python workspace that keeps project dependencies separate. Each project gets its own venv with its own installed packages, so Project A can use Django 4.0 while Project B uses Django 5.0 without conflict. Created with python -m venv myproject. Standard practice for any Python project.
W
Wireless internet — radio waves that connect your devices to your router without cables. Convenient but less stable than ethernet. Wi-Fi signals can be blocked by thick walls, interfered with by microwaves, and eavesdropped on if not encrypted. Always use a password on your Wi-Fi network.
A modern, fast, and simple VPN protocol. Much lighter and easier to configure than older VPNs like OpenVPN. Used by Tailscale, WG-Easy, and many self-hosted VPN setups. WireGuard creates an encrypted tunnel between your device and a server — ideal for securely accessing your home network from anywhere. Configuration is just a few lines of text. See: VPN Server Guide and Tailscale Guide
Microsoft's official way to run a real Linux terminal inside Windows — no virtual machine, no dual-boot. Most self-hosting and developer guides assume a Linux environment. WSL provides that environment on a Windows machine, so you can copy and paste commands directly. Installed with a single command: wsl --install. See: Command Line Guide
X
A format for storing data in a structured, human-readable way. Looks similar to HTML but is used for data, not web pages. You'll encounter XML in RSS feeds, configuration files, and some APIs. JSON has largely replaced it for modern use, but XML is still everywhere in older systems.
Y
A human-friendly format for writing configuration files. Docker Compose files (docker-compose.yml) use YAML. It uses indentation instead of brackets — like a well-formatted shopping list. If the indentation is wrong, YAML breaks, which is both its strength (readable) and its weakness (fussy).
Z
A security approach that assumes nothing inside your network is automatically safe. Instead of trusting everything behind the firewall and only guarding the edges, zero trust verifies every request — who is asking, from what device, for what — no matter where it comes from. In practice for a small business it means: separate accounts for everything, no shared logins, require authentication to reach internal tools, and give each person and program only what they need. It exists because most successful attacks come from inside, using a stolen login. See: Securing AI Agents
A security vulnerability that the software maker doesn't know about yet — they've had "zero days" to fix it. Zero-day exploits are the most dangerous because there's no patch available. This is why automatic updates matter: once a vulnerability is discovered, the clock starts ticking.
End-to-end encryption where even the service provider cannot access your data — they hold zero keys. Proton Mail and Tutanota use this model: your emails are encrypted on your device before they reach the server. Even if the provider is compelled by a court order, they have nothing to hand over because they can't decrypt your data. This is stronger than standard encryption where the provider holds the keys and could theoretically access your content. See: Email Privacy Guide
File formats that bundle multiple files into one and compress them. ZIP is the universal format (Windows, Mac, Linux all support it). Tar is the Linux equivalent, often combined with gzip compression (.tar.gz files). When you download software or share a folder, it's usually as a ZIP or tar archive.
Missing a term?
This glossary grows with the site. If you encountered a term in one of our guides that isn't defined here, let us know and we'll add it. The goal is that every technical word in every guide has a plain-English definition one click away.
Need More Help?
StarCaller Academy offers 1-to-1 sessions to help you with any of these topics and more.