Easy to start: you can share unfinished content early, exposed to many eyes
Have a simple, consistent page layout
Easy to create and maintain structured, up-to-date documents:
easy to access through the web, with simple login or without any login
easy to modify, no need to know HTML
easy to link pages
easy to create simple and consistent pages
easy to search
easy to extend with external pages.
Don't need to go to another colleague or IT dept to update the documentation = low resistance to keeping documentation up to date.
DokuWiki is even better for documentation
Easy to modify:
future links: links to non-existing pages are red
table of contents for each page
Supports multiple ways of including code examples
Sophisticated but easily administrated access control through user-friendly ACL and User Management GUI
Simple but powerful Configuration Manager interface for control over features of not only DokuWiki core but also most plugins and themes. If you are not a PHP expert or don't have time to waste fiddling with conf – no problem!
Datafiles are stored in plain text, so:
are readable even if your DokuWiki installation doesn't work anymore
easy to back up, through server scripts or FTP/sFTP
can easily be read, modified, compared, generated with external (non-wiki) programs
and easily moved from one DokuWiki-installation to another