If you use wikis or discussion groups that are open to the public at large, you may want your users to register to access them. You can either require registration or make it optional.
These registered users are called community users. They can make their own accounts and participate in discussion groups or wikis. They cannot access bugs or cases in any way.
In addition, community users are allowed to download and install the screenshot tool, allowing them to submit cases to public projects that include screenshots.
Community users do not require FogBugz licenses. To use this feature, go to Settings | Site, then the Authentication tab, and turn on the Community Users feature.