A featured snippet is the boxed, direct answer Google has long shown at the top of results. "Position zero". Lifting a sentence, list, or table straight from a page to answer a query without a click.
It's worth knowing because it's the direct ancestor of AI Overviews and AI answers, and the same content mechanics win both. Google earned snippets by extracting a clean, self-contained answer from a well-structured page; AI engines do a richer version of exactly that. The page that gets lifted is the one that states the answer plainly, near the top, in a format (short paragraph, list, table) a machine can pull out whole.
So the snippet-era playbook still pays off: answer the question directly and early, use clear headings that match how people ask, and put facts in lists and tables. The difference is that snippets sent a (shrinking) click, while AI answers are often fully zero-click. Making it even more important to be the cited source.