This is officially termed the ICAO (International Civil Aviation Organization) code. The ICAO is a United Nations department. Initially used by the US military, the code has since gained pervasive adoption by the airlines and is used throughout all civil aviation.
Use this code to spell words during radio transmissions or to give (code)names to persons, objects, places, drills, ...
Alpha
Bravo
Charlie
Delta
Echo
Foxtrot
Golf
Hotel
India
Juliet
Kilo
Lima
Mike
November
Oscar
Papa
Quebec
Romeo
Sierra
Tango
Uniform
Victor
Whiskey
X-ray
Yankee
Zulu