The guides below answer the questions people actually ask about the clipboard: how copying works and why it sometimes silently fails, how to wipe a password out of the clipboard after you paste it, how to keep more than one entry at a time, and what MIME type a given file turns into when a browser handles it. Each one is written to be read on its own, and each one links back to the clipboard inspector so you can verify the behaviour on your own machine rather than taking our word for it.
If you are after the deeper, code-level material — paste event internals, the async Clipboard API, DataTransfer, sanitising pasted HTML — that lives on the blog.