This includes services on the ramp or apron, such as:
Guiding the aircraft into and out of the parking position (by way of aircraft marshalling),
Towing with pushback tractors
Lavatory drainage
Water cartage (typically non-potable for lavatory sink use)
Air conditioning (more common for smaller aircraft)
Airstart units (for starting engines)
Luggage handling, usually by means of beltloaders and baggage carts
Gate checked luggage, often handled on the tarmac as passengers disembark
Air cargo handling, usually by means of cargo dollies and cargo loaders
Catering trucks
Refueling, which may be done with a refueling tanker truck or refueling pumper
Ground power (so that engines need not be running to provide aircraft power on the ground)
Passenger stairs (used instead of an aerobridge or airstairs, some budget airlines use both to improve turnaround speed)
Wheelchair lifts, if required
Hydraulic mules (units that provide hydraulic power to an aircraft externally)
Deicing