What is Claude Code?

Claude Code is an agentic coding tool that lives in your terminal. It understands your codebase, can edit files, run commands, search the web, and help you build software faster — all through natural language conversation.

Think of it as a senior developer pair-programming with you, except it can read your entire codebase, execute commands, and make changes across multiple files simultaneously.

How is it different from ChatGPT or a chatbot?

Regular AI chatbots work in a browser. You paste code in, get code back, then manually apply changes. Claude Code is fundamentally different:

• It lives in your terminal — right where you already work
• It reads your actual files — no copy-pasting needed
• It runs real commands — tests, builds, git operations
• It edits your code directly — with your approval
• It understands context — your project structure, dependencies, conventions
• Voice mode — talk to Claude instead of typing with /voice
• Desktop and IDE — also available as a VS Code extension and JetBrains plugin

What can Claude Code do?

Here's a taste of what's possible:

• Ask questions about your codebase: "How does the auth flow work?"
• Write new features: "Add a search endpoint to the API"
• Fix bugs: "The login page crashes when email is empty — fix it"
• Refactor code: "Convert this class component to a hook"
• Run tests: "Run the test suite and fix any failures"
• Git operations: "Create a PR for these changes"
• Explain code: "What does this regex do?"

The permission model

Claude Code asks for your approval before taking actions. You control what it can do:

• Read files — always allowed
• Edit files — asks permission (or auto-approve in settings)
• Run commands — asks permission for each command
• Web access — can search and fetch URLs when needed

This means you stay in control while Claude handles the heavy lifting.

How it works under the hood

1. You type a natural language request
2. Claude reads relevant files from your project
3. It formulates a plan (sometimes visible, sometimes implicit)
4. It executes actions: editing files, running commands, searching
5. It validates results and iterates if needed
6. You review and approve the changes

Next steps

In the next lesson, you'll install Claude Code and run your very first command. Let's go!