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. In classical NATO terminology the three basic military branches are army, air force 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:
- In Italy the Carabinieri
- In France the National Gendarmerie
- In Norway the Cyber Force
- In Poland the Polish Special Forces
- In Russia the Russian Airborne Troops, the Russian Aerospace Defence Forces, and the Strategic Missile Troops
- In South Korea the Marine Corps (Haebyeongdae)
- In the United States the Marine Corps and the Coast Guard
- Emblems of some countries
Historical development 
The military branches came into being in line with military technical progress and have been developed permanently. With that background, 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.