Terminal (or console)
A window where you type text commands to tell the computer what to do, instead of clicking with the mouse.
Like sending written instructions to your computer instead of pointing at buttons.
CLI
Command Line Interface. A program you use by typing in the terminal. Claude Code is a CLI.
Command
An order you type in the terminal for the computer to do something. For example, 'ls' lists the files in a folder.
Directory
The same thing as a folder. Developers usually say 'directory'.
Repository (repo)
A project folder whose change history is tracked with git. It can be on your computer and/or on the internet (GitHub).
Like a folder with a built-in time machine.
git
A tool that saves the history of all changes in your project, so you can go back or see what changed and when.
Like version history for a document, but for code.
Commit
A 'save point' in git. Each commit captures how your project looked at that moment, with a message explaining what you changed.
Like a snapshot of your project's state with a label describing it.
GitHub
A website where you can store your repositories online, share them, and collaborate with other people.
Branch
A parallel line of work in git. It lets you make changes without touching the main version until you're sure.
Like making a copy to experiment without breaking the original.
Pull Request (PR)
A proposal to add your changes to the main project, so someone can review them before accepting them.
API
Application Programming Interface. A way for two programs to talk to each other. For example, a website that checks the weather uses a weather service's API.
Like a restaurant waiter: you order, they bring what the kitchen prepares, without you going into the kitchen.
API key
A secret password that identifies who is using a service. Claude Code needs your Anthropic API key to work.
Like your personal ID to access a service.
Frontend
The part of an application that the user sees and uses: buttons, text, colors, forms.
The storefront and showroom of a shop.
Backend
The part you don't see: the logic, the database, the calculations. It works 'behind the scenes'.
The warehouse and back office where everything is managed.
Database
An organized place where an application's data is stored (users, products, messages...).
Like a giant filing cabinet, organized and searchable instantly.
Framework / Library
Code already written by other people that you reuse so you don't start from scratch. For example, React is a library for building interfaces.
Like using IKEA furniture instead of making every screw yourself.
Dependency
An external library your project needs to work. They are usually installed with npm or pip.
npm
Node.js's package manager. It lets you install JavaScript libraries with a command.
Package
A library packaged and ready to install. 'Installing a package' = adding someone else's code to your project.
Function
A named block of code that does a specific task and you can reuse as many times as you want.
Like a recipe: you write it once and use it whenever you want.
Variable
A name that stores a value (a number, text...) to use later.
Like a labeled box where you keep something.
Bug
An error or flaw in the code that makes it not work as it should.
Debug
The process of finding and fixing bugs.
Stack trace / Traceback
The long text that appears when something fails. It shows where and why the program broke. It's very useful: copy the whole thing when asking for help.
Deploy
Publishing your project on the internet so other people can use it. Vercel, for example, deploys websites.
Server
A computer (usually on the internet) that runs your application and responds to users' requests.
localhost
Your own computer acting as a server, to test your project before publishing it. It usually looks like 'localhost:3000'.
JSON
A text format for storing and sharing data in an organized way. Almost all applications use it to communicate.
Environment
The set of programs and settings where your code runs. Your computer is one environment; a server is another.
Environment variable
A configuration value that lives outside the code (like an API key), so you don't write secrets directly in files.
Hook
In Claude Code, a script that runs automatically when something happens (before or after an action). It helps automate tasks.
MCP
Model Context Protocol. The way Claude Code connects to external tools like databases or the browser.
Like a universal plug for connecting tools to the AI.