Air traffic controllers are people who operate the air traffic control system to expeite and maintain a safe and orderly flow of air traffic and help prevent mid-air collisions. They apply separation rules to keep each aircraft apart from others in their area of responsibility and move all aircraft safely and efficiently through their assigned sector of airspace. Because controllers have a demonstrably large responsibility while on duty, the ATC profession is often regarded as one of the most difficult jobs today, and can be notoriously stressful. Although the media frequently refers to them as "air controllers," or "flight controllers" no controller ever would. They are called air traffic controllers, air traffic control officers (ATCOs), air traffic control specialists, or simply controllers.