A Skill is a set of instructions that help LLMs perform specific tasks really well.
Within your LLM system (ChatGPT, Claude, etc.), you must add a Skill.md file. Optionally, you may add an entire Skill zip file which includes References, Scripts and Assets.
The References/ folder contains other .md files providing in-depth instruction for a specific task, background materials, policies, or source documents.
The Scripts/ folder contains code when code is needed for the output format, tests, or file generation.
The Assets/ folder contains reusable templates, images, sample files, or other supporting assets.
Always start light-weight with a Skill.md file. Then add optional resources only when they help the system do the work more reliably, save human time, or produce a better result.