Is a history of changes available for each page of the wiki?
This is also known as 'Version History' 'Revision History' or just 'History'. It is a display built into the wiki software, which shows a list of wiki edits which have taken place on a given page. Implementations vary, but typically you should have access to the following information on each edit.
While we should remain open minded about alternative implementation approaches, the page history display is a place where a lot of immature over-simplified wiki implementations come unstuck. If any of the above features are missing, you need to think carefully (and read some of the supporting information here) to decide you if you should try to manage without it, or just choose a better wiki engine. The above list is roughly in order of importance, but any wiki software which doesn't offer the first three features, should really not be taken seriously!
Typically you can follow links from the page history display to the actual content of the previous versions, and from there you can restore a previous version. Note that this is an *essential feature*. You must be able to retrieve old versions of page contents. This is the concept of “reversible change”. Without it the wiki concept doesn't work.
The number of Revision diffs available can sometimes be limited.