Final answer:
An ARTCC provides ATC services to en route aircraft, ensuring safe and efficient air traffic flow in controlled airspace at cruising altitudes.
Step-by-step explanation:
The primary function of an ARTCC, which stands for Air Route Traffic Control Center, is providing ATC (Air Traffic Control) service to en route aircraft. The ARTCC is responsible for managing air traffic in a wide area, providing services to ensure safe and efficient flight experiences for aircraft traveling through controlled airspace at cruising altitudes, typically away from the immediate vicinity of airports. These centers are crucial for coordinating the flow of traffic, providing aircraft separation, and communicating important flight information to pilots.