Also: Fixed Base Operator, Handling agent, Business aviation handling
The term comes from the United States. In Europe, people often speak of handling agents or business aviation handling. Either way, it is the company that looks after the aircraft, crew and passengers on the ground.
Typical services include welcoming passengers, baggage handling, coordinating passport and customs checks, fuelling, catering and arranging transfers directly to the aircraft.
As a passenger, the FBO is usually your first point of contact on the day of departure. The operator will tell you the exact meeting point and preferred arrival time before your flight.