oldid

Oldid is a query parameter used by MediaWiki-based wikis to reference a specific historical revision of a page. It identifies the revision by its revision ID (rev_id), a unique number assigned to each edit. When included in a page URL, the wiki renders the page as it existed at that revision, ignoring later changes. For example: https://en.wikipedia.org/w/index.php?title=Example&oldid=123456789.

Oldid links are useful for citing sources, comparing past and present content, or restoring pages to a previous state. If you add the diff parameter in combination with oldid, you can see the differences between that revision and another revision, for instance ?title=Example&oldid=123456789&diff=prev.

The oldid parameter is part of MediaWiki's revision system; it coexists with other parameters such as curid (the current revision ID) and diff, which control how revisions are displayed or compared. The rev_id is globally unique within a wiki, so oldid is a stable reference even if the page title changes, is moved, or the page is renamed.

Notes: Access to old revisions depends on the wiki's deletion and protection policies. Some revisions may be deleted or restored according to governance rules, and in rare cases a page or revision may not be accessible.

See also: curid, rev_id, timestamp.