Q: What is a single group/wiki?

A: The software is licensed based on the number of wikis you can create, rather than the number of users. In ProjectForum, each wiki acts as its own independent working space - its own set of pages, own set of users, etc.

Normally, if you have two different groups of people working on different things, they'd set up their own wiki, just to avoid "colliding" with each other. If you've got a group of people all more or less working on the same thing, it makes sense to have them share a single working space, i.e. a single wiki.

For example, you can visit one of our hosted sites at http://groups.projectforum.com/. Each of the items listed on the left is a single self-contained wiki, in this case all owned by different people and used for different things.

The licensing covers how many of these you want to create in the software - how you use each one, and if you have one or more than one is entirely up to you. A lot of people start with one, and as they end up using it for more different things, they decide to add more so they can split things off. Again, no limits on number of users per wiki, or pages, or anything else. If you have a chance to try the software, you'll get a sense of this.