Community of interest

A community of interest is a community of people who share a common interest or passion. These people exchange ideas and thoughts about the given passion, but may know (or care) little about each other outside of this area. Participation in a community of interest can be compelling, entertaining and create a 'sticky' community where people return frequently and remain for extended periods. Frequently, they cannot be easily defined by a particular geographical area.

In other words, "a community of interest is a gathering of people assembled around a topic of common interest. Its members take part in the community to exchange information, to obtain answers to personal questions or problems, to improve their understanding of a subject, to share common passions or to play." In contrast to a spatial community, "a 'community of interest' is defined not by space, but by some common bond (e.g. feeling of attachment) or entity (e.g. farming, church group)."

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Wikipedia