"Community theatre" generally refers to a nonprofit theatre company that serves a locality, relies heavily on volunteers, and does not use Equity (union) actors on a regular basis. Community theatres tend to be operated for local recreation, education, and commonly seek to obtain the patronage and production participation of the community as a whole.
Note that the spelling of "theater" or "theatre" is a matter of choice. "Theatre" is most common in Great Britain and France. In the United States, both spellings are used.