Thread:Support/About MediaWiki:Apihelp-gather-description/ksh/reply

Looks like there is no help page yet, but it's this thing:. A list of page titles stored in the database, which is rendered as a gallery. The extension sometimes calls them "Gather collections", sometimes "collections", sometimes "lists" and sometimes in other ways. Someone should file a bug to ask consistency, but apparently that's a hot topic for the maintainers.