The NATO phonetic alphabet was developed in the 1950s to be intelligible (and pronounceable) to all NATO allies in the heat of battle. It replaced other phonetic alphabets, for example the US military "able baker" alphabet.
The NATO phonetic alphabet is now widely used in business and telecommunications in Europe and North America, and has been approved by ICAO for use in international aviation.
The alphabet is used to spell out parts of a message that are critical or otherwise hard to recognize during voice communication. For instance the message "proceed to map grid DH98" could be transmitted as "proceed to map grid Delta-Hotel-Niner-Eight".
The NATO phonetic alphabet is as follows: