DokuWiki - Open Source Wiki

DokuWiki is a standard compliant, simple to use Wiki, mainly aimed at creating documentation of any kind. It is targeted at developer teams, workgroups and small companies. It has a simple but powerful syntax which makes sure the data files remain readable outside the Wiki and eases the creation of structured texts. All data is stored in plain text files – no database is required.
DokuWiki has many features but all of them are easy to learn. And many more can be added through the free plugin downloads