What is Claude Code: The Terminal Revolution Nobody Saw Coming

You paste code into a browser AI, wait for a response, paste the fix back into your editor, realize it broke something else, and repeat. Sound familiar? That loop is why Claude Code exists. If you're new here, explore the complete Claude Code guide for a full overview of what's possible.

Quick Win: See It Work in 2 Minutes

Open your terminal in any project folder and run:

npx @anthropic-ai/claude-code
claude "explain this codebase structure and find potential issues"

Claude Code reads your entire project, files, Git history, dependencies, and returns actionable insights. No copy-pasting. No context loss. It just understands.

What is Claude Code?

Claude Code is Anthropic's agentic coding assistant that runs directly in your terminal, IDE, or browser. Unlike chat-based AI tools, Claude Code has full access to your project files, can execute commands, and makes changes with your approval.

The paradigm shift: you become the main thread. Instead of manually shuttling context between AI and code, you delegate tasks and Claude handles execution. Think of yourself as a CPU scheduler, queuing up tasks while Claude processes them in parallel.

# Claude Code works where you work
claude "add authentication to the Express routes"
claude "write tests for the payment service"
claude "refactor this component to use React hooks"

How It Works

Claude Code runs locally and talks directly to Anthropic's API. No remote code indexing, no server-side processing of your code. Three capabilities make it powerful:

Full Codebase Awareness: Claude reads your file structure, Git history, and dependencies automatically. Ask about any part of your project and it already knows the context.

Agentic Execution: Claude does not just suggest code, it writes files, runs commands, creates commits, and verifies its own work. You approve each action.

Extensibility: Through MCP servers, Claude connects to databases, APIs, GitHub, and external tools to extend what it can do.

Key Features You Should Know

Plan Mode (shift+tab twice): Claude analyzes without changing anything. Perfect for understanding complex problems before committing to a solution.

Skills: Reusable instruction packages that teach Claude domain-specific workflows. Learn more about skills.

Hooks: Automated actions that trigger at specific points, like formatting code after every edit or blocking changes to production files.

Checkpoints: Automatic snapshots before each change. Press Esc twice to rewind if something breaks.

Subagents: Parallel workers for complex tasks. One agent builds the frontend while another sets up the backend.

Claude.ai vs Claude Code

This is not a small difference. It is the difference between having an advisor and having an engineer. Explore the full configuration options to customize behavior.

Getting Started

1. Install: Follow the installation guide (takes 2 minutes)
2. First Project: Complete the first project tutorial to see it work
3. Troubleshooting: Check common fixes if you hit issues
4. Go Deeper: Learn about permission management for safer workflows

Claude Code runs on Pro and Max subscriptions, or pay-as-you-go through the API. It works with Opus 4.5, Sonnet 4.5, and Haiku 4.5 models.

Ready to stop copy-pasting? Start with the installation guide and run your first command in under 5 minutes.