Wikis for Collaboration

This video from CommonCraft is a good introduction to wikis and how they can be used for collaboration:

Why a wiki and not a blog?
The purposes, author, and navigation are different for each.
A blog is usually written by only one person, although there are places that will let you create class (multi-editor) blogs. A blog always has the most recent content at the top and most will archive posts by month, so they no longer show on the page. Other people can make comments on a blog post, but cannot edit the original post.
A wiki is usually created for collaboration - a group editing or contributing to a page is common. The wiki creator can create the navigation, usually seen in a column at the side, or on the front page. This navigation system stays the same over time, so you can create a more permanent navigation for the site content.