A community can be set up by any user to provide a space to share documents, have online discussion, etc. It can be set up as protected and only accessed by authenticated users and further can be configured to require registration or not, etc. There are three types of communities which can be used for different purposes. The three types are: community, course website, and learning module. More detail is in the Community>Types help section. All communities can be configured to include features like announcements, discussion boards, document sharing, quizzes, events, polling, etc.
Notably, communities is one of the few modules of Elentra that is not organisation specific. That means you can see communities created within one organisation across all organisations and you can add users from any organisation to any community. When users are logged in they can access any of their communities without toggling between their organisations.
Often an organisation's staff maintains course website communities, committee communities, and learning modules. Individual users can create communities for their study groups, professional learning communities, sports teams, etc.