A diff (from the word "difference") is a web page displaying the difference between one version and another of a Wikipedia page. A particular version of a page is called a "revision"; each revision has a date and time of creation which can be seen in the page history. Clicking a "diff" link in a page's history will display the diff of two successive revisions.
Links to diffs are found on various special pages other than page histories, including the User contributions page which every user has, Recent changes, Related changes, and watchlists.
Discovered by embedding cosine similarity (sentence-transformers MiniLM, 384-dim).