What Skills are and how they work
Agent Skills are reusable markdown files that define how Claude should behave in specific contexts. Instead of re-explaining your standards, preferences, and procedures every session, you write them once as a Skill and Claude applies them automatically whenever the context calls for it.
Without skills, every Claude Code session starts from zero context about how you want things done. You might find yourself repeatedly typing: "Use TypeScript strict mode," "Add JSDoc comments," "Follow our error handling pattern," "Write tests for each function." Skills encode these standing instructions so you never have to repeat them.
When you send a message in Claude Code, the system scans your active skills and checks whether any of them should apply to the current context. Skills that match are automatically included in Claude's context — silently, without any action needed from you. The result is Claude that already knows your standards when it starts working.
Both Skills and CLAUDE.md provide persistent instructions, but they serve different purposes:
Think of CLAUDE.md as the general briefing and Skills as specialized playbooks for specific situations.
