A WikiProject is a collection of pages devoted to the management of a specific topic or family of topics within Wikipedia; and, simultaneously, a group of editors that use said pages to collaborate on encyclopedic work. It is not a place to write encyclopedia articles directly, but a resource to help coordinate and organize article writing and editing.
Despite the name, the purpose of Wikipedia:WikiProject is concerned not with project management, but the daily management, administration and editor support of the process of article creation, editing and completion.
The attached talk pages are a convenient forum for those interested in a particular project.
Participating
There is a central Directory of WikiProjects available which lists all known projects; for ease of navigation, it has been split into sections by projects topic:
