Help:Page history

A page history shows the order in which edits were made to any editable Wikipedia page, the difference between any two revisions, and a menu of special external tools. A page history is sometimes called revision history or edit history.

If you want to view a page's history, go to the page (e.g., Cat) and click the "View history" tab in the upper-right section of the screen.
10 minute video introduction to the View History feature.

You can view a page's history by clicking the “View history” tab at the top of the associated page (pictured right).

The page history contains a list of the page's previous revisions, including the date and timein UTC by defaultof each edit, the username or IP address of the user who made the change, and an optional edit summary that briefly describes or explains the change. For example, the page history for this help page shows that it was first created on September 20, 2004, and that it has been changed more than 500 times since then.