Glossary

🤖 AI and prompts

prompt

What you type to an AI. The more clearly you describe the goal, the materials and the shape of the result, the better the answer. How to do it is in the guide How to write prompts.

prompting

Writing and tuning prompts until the AI does what you need.

LLM (large language model)

A model trained on a huge amount of text that builds its answer word by word. It's the "brain" of ChatGPT, Claude, Gemini or Grok.

model

A specific AI "brain" in a specific version. One app often offers several models, faster and smarter ones. The overview is in Which AI for what.

chatbot

An app where you write to an AI like in a chat, such as ChatGPT, Claude, Gemini or Grok.

AI agent

An AI that breaks a task into steps on its own and carries them out: it reads files, runs commands, changes code. For example the agent in Cursor or Claude Code.

hallucination

When an AI makes up a fact, a quote or a source and presents it confidently. That's why you should check important things.

token

A piece of text the model works with, roughly part of a word. Text length, limits and price are all measured in tokens.

context window

How much text the model can "keep in its head" at once: your messages, attachments and its own answers. Whatever doesn't fit, it stops seeing.

reasoning mode

A mode in which the model thinks longer before answering. Good for logic, calculations and code. It's slower.

system prompt / custom instructions

Instructions the AI gets at the start of every conversation: who you are and how it should answer you. Where to put them in chat apps is in Rules for chat.

persona

The role and style in which the AI presents itself: tone, how it addresses you, how it refers to itself. It's set in the rules.

multimodal

An AI that handles images, audio or video as well as text.

voice mode

You talk to the AI out loud and it answers by voice. Good for languages or practising a conversation.

RAG

A method where the AI first searches for passages in your documents and then answers from them. That's how tools that answer from uploaded materials work.

knowledge base

A collection of documents the AI draws its answers from instead of making things up.

Custom GPT, Gem, project

Your own version of a chatbot with a fixed role, instructions and materials. In ChatGPT it's called a GPT, in Gemini a Gem, in Claude a project.

deepfake

A fake video, photo or voice of a real person made with AI.

prompt injection

An attack where instructions for the AI are hidden on a website, in a document or in an email, to make it do something you don't want. It's mainly a risk for agents that read other people's content.

🛠️ AI tools and setup

IDE

A program for writing code, such as VS Code or Cursor.

Cursor

A code editor with an AI agent that can change files and run commands. The how-to is in the Cursor guide.

Claude Code

An AI agent from Anthropic that works directly with your project in the terminal or in your editor.

MCP

Model Context Protocol. A standard for connecting AI to other tools and data: files, a browser, a database.

rules

Text with instructions the AI reads at the start of its work: how to answer, what it may and may not do. How to write them is in the Set up AI section.

User Rules

Your personal rules in Cursor (Customize → Rules). They apply to all projects.

AGENTS.md

A file in the project root with rules for AI agents. Cursor and other agents read it; Claude Code only does when there's no CLAUDE.md in the project.

CLAUDE.md

A rules file for Claude Code. Your personal one is in ~/.claude/CLAUDE.md, the project one in the project root.

.mdc

A project rules file for Cursor in the .cursor/rules/ folder. Cursor ignores a plain .md there.

Plan mode

The AI only plans and suggests; it doesn't change files. Safe for starting out.

Agent mode

The AI may change files and run commands.

hook (for agents)

A script that runs before or after an agent's action. It can, for example, stop a dangerous command. The how-to is in Guardrails and safety.

allowlist

A list of commands the agent may run without asking. For anything else, it asks.

skill

A bundle of instructions and files that an agent loads when it handles a particular type of task.

subagent

A helper agent that the main agent hands part of the work to, with its own brief.

v0

An AI tool from Vercel that generates a web interface from a description.

💻 Code and Git

terminal

A window where you type text commands instead of clicking with the mouse.

PowerShell

The default command line in Windows.

WSL

Linux inside Windows. Handy for developing websites and servers.

bash / zsh

Command lines on Linux and macOS.

shell

The program that reads and runs your commands in the terminal. Bash and PowerShell are both shells.

npm / pnpm / yarn

Package managers for JavaScript and TypeScript.

package

A ready-made library you add to a project with a command, such as npm install.

build

Turning source code into a finished form that can be run or deployed.

dev server

A local development version that runs only on your machine, for example at localhost:3000.

production

The live version that users see.

staging

A test environment between development and production.

deploy

Putting a website or app on a server so it's available to everyone.

Git

A program that remembers every saved version of your project. When something breaks, you go back. More in the GitHub guide.

repository (repo)

A project folder tracked by Git, often stored on GitHub too.

commit

A saved version of the project with a description of the change. It's made on your computer.

push

Sending commits to a server, such as GitHub.

pull

Downloading changes from the server to your machine.

branch

A separate line of development where you try out changes without risk to the main version.

main / master

The main branch, usually the one running in production.

merge

Merging one branch into another.

rebase

Rewriting history so your commits build on the latest state of another branch. Don't let an agent do it without your permission.

PR (pull request)

A request to merge a branch, which someone reviews before it's merged.

diff

A listing of only the changed lines; added ones are marked +, removed ones −.

regression

When a new change breaks something that worked before.

unit test

A test of one small part of the code, such as one function.

integration test

A test of several parts together, such as the interface, the API and the database.

e2e test

A test of a user's whole journey through the app from start to finish.

linter

A tool that checks code for errors and style, such as ESLint.

formatter

A tool that formats code automatically, such as Prettier.

refactoring

Rewriting code without changing what it does, to make it more readable and simpler.

secret, API key

A sensitive key to an API, a database or an account. It doesn't belong in Git or in a chat.

.env

A file with secret keys in the project root. It belongs in .gitignore.

.gitignore

A list of files Git doesn't track, such as node_modules or .env.

Docker

An app packaged together with its environment into a "container" that runs the same anywhere.

CI/CD

Automatic testing and deployment of new code after every change.

Node.js

An environment that runs JavaScript outside the browser, for example on a server.

TypeScript

JavaScript with types. More errors are caught before the code runs.

JSX / TSX

React syntax in which HTML is written directly inside JavaScript or TypeScript.

framework

A ready-made skeleton for apps, such as Next.js, Django or Laravel.

library

A ready-made piece of code you add to a project and use.

component

A reusable piece of the interface, such as a button or a card.

🌐 Web and development

API

An interface through which programs communicate and exchange data.

endpoint

A specific API address, such as /api/users/42.

frontend

The part of a website the user sees and uses in the browser.

backend

The part that runs on the server: data, logic, sign-in.

fullstack

A developer who does both frontend and backend.

stack

The set of technologies you use on a project.

SaaS

Software as a service. An app in the cloud that you pay a subscription for.

landing page

A page with a single goal, where visitors arrive from an ad, for example: sign-up, purchase, contact.

dashboard

An overview screen with charts, tables and numbers.

CMS

An admin area where you edit a website's content without programming, such as WordPress.

MVP

The smallest version of a product that already works and can be shown to people.

UX / UI

UX is how a product is used. UI is how it looks.

mockup

A visual design of how a website or app will look.

wireframe

A rough sketch of a page's layout without colours or final design.

responsive web

A website that adapts to both a phone and a large monitor.

SSR / CSR / SSG

Where the page is put together: on the server, in the browser, or ahead of time during the build.

cache

A cache. Whatever has been loaded or calculated once is available faster the second time.

SQL / NoSQL

Table-based and document databases, such as PostgreSQL and MongoDB.

Cloudflare Workers

Code that runs on Cloudflare's servers around the world, without a server of your own. How to put a website on Cloudflare is in Deploying a website.

SEO

Changes to a website so people find it more easily on Google and other search engines.

A/B testing

Two versions of a page for different visitors. The results show which one works better.

📣 Marketing and content

hook (in content)

A hook at the start of a video or text that holds attention in the first seconds.

CTA

A call to action, such as a "Buy" button or the line "Subscribe to the channel".

USP

Your main advantage, what sets you apart from the competition.

tone of voice

The tone and style a brand uses with its customers, such as casual and funny, or formal.

naming

Coming up with a name for a company or product that's catchy and still available.

repurposing

Reusing content in another format, such as turning one video into three short ones and an article.

cross-sell

Offering a related product with a purchase, such as laces with shoes.

B-roll

Extra footage cut over the main video, such as hands on a keyboard while you're talking.

intro / outro

The opening and ending of a video, song or podcast.

💼 Work and the office

workflow

A work process: how the individual steps follow each other.

KPI

A key indicator that tells you whether things are going well, such as revenue or the number of sign-ups.

ATS

A system companies use to sort CVs, often automatically by keywords.

VLOOKUP

An Excel function that finds a value in another table. In the Czech version of Excel it's called SVYHLEDAT.

TL;DR

"Too long; didn't read": a very short summary of a long text.

Is a word missing? Ask an AI, for example: "Explain in one sentence what [word] is, and give one example." It works in any chat.