A community on interests.me is a shared, collaborative website (and weekly email) which many local organisations contribute to. It includes a calendar of local events and an online noticeboard.
To contribute, an organisation needs to join the community on interests.me, which is a collection of organisations which have something in common, brought together by the community manager or administrator.
Usually communities are local, and based around a geographic area - for instance Woking.interests.me is the local community for organisations and groups based in Woking.
However, a community can sometimes be national or international, if the organisations collected together have something in common - for instance if they are all involved in the same cause. For an example of a national community, see LGBTUK.interests.me