Confluence is a WikiLike content management system.
Confluence has spaces that are separate. This is ideal for project documentation. Each team only cares about their own project. See WikiNameSpace.
Confluence has memberships, so some spaces can have their pages hidden from people that aren’t members of the space. This is good for corporate life.
Confluence has a table of contents that is always on. A big problem of wikis is the freedom to organize, and the unwillingness of people to organize. Often we end up with a big mess. In Confluence, the table of contents is a tree and you add pages to that tree. Automatic minimal organization.
Confluence has a VisualEditor integrated, with multiple people editing simultaneously. This is both fantastic and confusing. If you and your buddy are editing a page and you decide to save the page, Confluence will tell you that your buddy has unsaved changes that you will be saving as well. Since you never know what your buddies are writing elsewhere on the page you always answer yes. It’s weird. And when neither saves, the changes are still available as “unpublished changes”. Everything is full of subtleties when it comes to simultaneous editing.