A skill is a written instruction file your AI follows every time, so you stop re-explaining the same task. Pick one repeatable task you do weekly, answer the questions below, and you get a SKILL.md file that works in Claude, ChatGPT, or whatever you use.
Download it and keep it next to your FOUNDATION.md. To use it: give your AI the foundation file first, then this skill file, then your inputs for the day. Same result, every time, whoever runs it.