The term "WikiProject" is used for projects created for the purpose of managing a specific family of information within Wikipedia. For example, Wikipedia:WikiProject Economics organises articles related to Economics, including economic terms, theories, and economists.
A WikiProject is a resource to help coordinate and organize article writing. Its attached talk page is a convenient forum for those interested in a particular project. WikiProjects can also have associated Portals.
Some projects, like the Tip of the day project, coordinate internal Wikipedia processes rather than article content directly (though not all of these use the term "WikiProject").