Air force

Air force is the part of a country's military forces that uses aircraft and fights in the air [Cambridge Dictionary].
Four main missions: strategic bombardment, support of ground operations, air defense, and air transport[Trest W.].
The primary weapon systems of air forces are such military airplanes as fighters, bombers, fighter-bombers, attack aircraft, reconnaissance craft, and training craft. Since the mid-20th century, the air forces of some of the world’s major powers have also operated those nations’ contingents of land-based intercontinental ballistic missiles and nuclear-armed long-range bombers. A nation's armed forces' army and naval branches may also operate aircraft, but the air force usually remains the prime instrument of a nation’s air power. The organization, command structure, and personnel grades within air forces vary from country to country [Britannica].

Sources:

Air force. Britannica. Retrieved from: https://www.britannica.com/topic/air-force

Air force. Cambridge Dictionary. Retrieved from: https://dictionary.cambridge.org/dictionary/english/air-force

Trest W.(1998). Air Force Roles and Missions: A History. Washington, D.C.: Library of Congress