If you have spent any real time with Claude Code, you have probably noticed the same problem I did. You write the same instructions in the prompt every other day. "Use four-space indentation here." "Always run the linter after edits." "Format commit messages this way." After the third or fourth repeat, it stops feeling like a prompt and starts feeling like missing config. Skills are how Claude Code fixes that. A skill is a small folder, with one markdown file inside, that Claude pulls into the conversation only when your request actually needs it. No setup screen. No plugin manager. Just a file in a folder and a one-line description telling Claude what it is for. This post is a clean walkthrough for 2026. What a skill actually is, how to write your first one, where to put it, and how it compares to the two things people often confuse it with: slash commands and subagents. What a Claude Code Skill actually is At the most basic level, a skill is a directory with a single file called SKILL.md inside it.…