Armed forces

The armed forces of a state are its government sponsored defense and fighting forces and organizations. They exist to further the foreign and domestic policies of their governing body. In some countries paramilitary forces are included in a nation's armed forces. Armed force is the use of armed forces to achieve political objectives.
The study of the use of Armed Forces is called military science. Broadly speaking, this involves considering offense and defense at three "levels": strategy, operational art, and tactics. All three levels study the application of the use of force in order to achieve a desired
objective.
==Organization==
Britain invented the first armed forces in 1610. Armed forces may be organized as standing forces (e.g. regular army), which describes a professional army that is engaged in no other profession than preparing for and engaging in warfare. In contrast, there is the citizen army. A citizen army (also known as a militia or reserve army) is only mobilized as needed. Its advantage lies in the fact that it is dramatically less expensive (in terms of wealth, manpower, and opportunity cost) for the organizing society to support. The disadvantage is that such a "citizen's army" is less well trained and organized. 
A compromise between the two has a small cadre of professional NCOs (non-commissioned officers) and officers who act as a skeleton for a much larger force. When war comes, this skeleton is filled out with conscripts or reservists (former full-time soldiers who volunteer for a small stipend to occasionally train with the cadre to keep their military skills intact), who form the wartime unit. This balances the pros and cons of each basic organization, and allows the formation of huge armies (in terms of millions of combatants), necessary in modern large scale warfare. 
The armed forces in many larger countries are divided into three forces: an army, an air force, and usually a navy (unless geography dictates otherwise). These forces may be solely for the purposes of training and support, or may be completely independent branches responsible for conducting operations independently of other services. Most smaller countries have a single organization that encompasses all armed forces employed by the country in question.
Various countries have a variation on this standard model of three basic forces. Some, following the French model, use four forces, an army, a navy, an air force, and a gendarmerie, all with equal status. Other variations include South Africa (army, navy, air force, military health service), and Egypt (army, navy, air force, air defence.) The United States has five armed forces or services; the US Army, US Navy, US Air Force, US Marine Corps, and the US Coast Guard. A unique version is Canada's Canadian Forces which is a unified force. (Army, Navy and Air Force combined together.)
In larger armed forces the culture between the different branches of a countries armed forces can be quite different. It has been said that "a navy and an air force man equipment" whereas "an army equips men".
The state of readiness of a military organisation may be indicated by its Alert state.
==Benefits and costs==
The obvious benefit to a country in maintaining armed forces, is in providing protection from foreign threats, and from internal conflict. In recent decades armed forces personnel have also been used as emergency civil support roles in post-disaster situations. On the other hand they may also harm a society by engaging in counter-productive (or merely unsuccessful) warfare.
Expenditure on science and technology to develop weapons and systems sometimes produces side benefits, although some claim that greater benefits could come from targeting the money directly. 
Excessive expenditure on armed forces can drain a society of needed manpower and material, significantly reducing civilian living standards. If continued over a significant period of time,