Military branch (also service branch or armed service) is according to common standard the subdivision of the national armed forces of a sovereign nation or state. As to classical NATO terminology the three basic military branches are Army, Air Force (in some countries also Luftwaffe or Luftstreitkräfte) and Navy.
Countries which do not have access to any of the high sea or any oceans generally do not have a national navy.
In some countries there might be other military branches. In addition to the above mentioned military branches there are for example:
The military branches cam into being in line with military technical progress and have been developed permanently. With that bag round, the air force was established early in the 20th century as one of the latest armed service.
The army is traditionally the oldest – and in many countries the biggest armed service.