Some prompts you'll type over and over. "Review the changes I made and suggest improvements." "Check all pages for broken links." "Create a new blog post with the standard template."
Typing these every time is tedious. Custom commands let you save them.
Instead of pasting a paragraph, you type /review or /check-links or /new-post. Same result, less typing. Think of them as recipes: write the instructions once, use them forever.
Where Commands Live
Custom commands are Markdown files in a .claude/commands/ folder:
my-website/
.claude/
commands/
review.md
check-links.md
new-post.md
index.html
...
Each .md file is one command. The filename (without .md) becomes the command name. So review.md becomes /review. Simple as that.