Advantages
anyone can edit
easy to use and learn
Wikis are instantaneous so there is no need to wait for a publisher to create a new edition or update information
people located in different parts of the world can work on the same document
the wiki software keeps track of every edit made and it's a simple process to revert back to a previous version of an article
widens access to the power of web publishing to non-technical users
the wiki has no predetermined structure - consequently it is a flexible tool which can be used for a wide range of applications
there are a wide range of open source software wiki's to choose from so licensing costs shouldn't be a barrier to installing an institutional wiki