What is a local intergroup's responsibility? Who creates intergroups and how do they fit into the service structure?
Typically intergroups are created by a number of groups in a given location and function as the contact point between the public and the groups. While most groups are too small to staff their own phone line or office an intergroup can serve that function for many groups.
Historically the main function of intergroups has been to answer the phones at the local AA phone number and to publish directories of the local AA meetings. Sometimes they also help organize multi-group events - like local conferences, dances, picnics, camp outs, "alcathons" or dinners. The scope of what an intergroup is responsible for is determined entirely by the groups served and can vary significantly.
Unlike service districts and area offices, intergroups function apart from the regular service structure and responsible only to the groups they intend to serve. Usually their operating budget comes exclusively from donations by their constituent groups.
Intergroups are created as needed and there is no formal process for starting one. Some function very informally while some in large cities are incorporated non-profits. Sometimes two intergroups in close proximity will overlap in the locations they intend to serve as there are no formal boundaries for intergroups.