The Italian Armed Forces encompass the Italian Army, the Italian Navy, the Italian Air Force and the Carabinieri. The President of the Italian Republic heads the armed forces as the President of the Supreme Council of Defence. The total number of active military personnel in 2011 is 319,529 (including the national gendarmerie, but excluding Guardia di Finanza, a military corp under the authority of the Italian Ministry of Economy). Italy currently runs the ninth or tenth highest military budget in the world.

Article 11 of the Constitution of Italy says:

Article 52 says:

And part of article 87 says:

The Italian Army (Esercito Italiano) is the ground defense force of the Italian Republic. It has recently (July 29, 2004) become a professional all-volunteer force of 115,687 active duty personnel. Its most famous combat vehicles are Dardo, Puma, Centauro and Ariete, and Mangusta attack helicopters, recently deployed in UN missions.

The armed forces of a country are its government-sponsored defense, fighting forces, and organizations. They exist to further the foreign and domestic policies of their governing body, and to defend that body and the nation it represents from external and internal aggressors. 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.

In most countries the basis of the armed forces is the military, divided into basic Armed services. However, armed forces can include other paramilitary structures. For example, according to the Lithuanian law on organisation of system of national defence and military service (version actual from November 11, 2004), the Lithuanian armed forces in case of war also include border guards, public police service, parts of Lithuanian Riflemen's Union and guerrillas.