Military is a governmental unit comprised of persons who are authorised by the government for the use of deadly weapons and application of deadly force for the offence or the defence of a country.

Majority of the countries across the world have military forces, and those that do not, usually have signed treaties with either neighbouring countries or those of greater military power for protection. In addition to defending the nation and waging war against another, military has been used for internal population control, as the means of overthrowing a government, as a relief force in times of a disaster, as well as guard against important or otherwise under threat areas.

The biggest and the most prominent military alliance is the North Atlantic Treaty Organisations (NATO). Unlike the single country's military, the NATO works as an intergovernmental defence organisation whereas, if one member is under threat, the rest will come to aid. Each member country contributes either military personnel, aid or monetary support. Although inactive until the break-up of Yugoslavia, NATO is now present in a number of countries and engaged in a number of conflicts and is considered as one of the strongest intergovernmental militaries in the world.

The largest military in the world, by personnel, is the People's Republic of China, where almost seven million people are in the military service. In terms of military equipment however, the leading military is that of the United States of America, with over five times the military budget than next biggest military, People's Republic of China.

Military and army area not to be confused with one another. As discussed above, military is a unit of government authorised, armed and authorised by the government to use deadly force for protection of a nation, while an army is a division of a military. An example of an army can include Navy, Marines, Air Force or Coast Guard.