Claude Code is a command-line AI agent that reads, edits, and runs code and files on your computer based on plain English prompts. It handles everything from file management and data gathering to custom workflows, with built-in tools for permissions, version control, and session memory.

• Claude Code executes actions (editing files, running commands, installing packages) directly in your terminal instead of just chatting about code, pausing for approval on risky actions unless pre-approved via settings.local.json or blocked via a deny list.
• Context window fills up with conversation/file history, so at 85–95% capacity you need /compact (summarize) or /clear (reset), and billing is token-based (~0.75 words/token) tracked via /cost.
• You can switch models on the fly with /model (Haiku for speed/cost, Sonnet as default, Opus for max power), and CLAUDE.md plus automatic memory persist project-specific context and preferences across sessions.
• Customization extends via slash commands, on-demand "skills," and hooks that trigger background scripts (like auto-formatting), giving fine-grained control over autonomy and tool access.