In the sphere of the armed forces two types of units can be counted on, those on active duty and those acting as reserves. As far as active military personnel are concerned The Peoples Republic of China has the largest number of active armed forces numbered at around two million two hundred and fifty five thousand. China is also the most populous country in the world; it has the largest air force as well. The Second largest armed forces belong to the United States at approximately one million four hundred and seventy four thousand. India ranks in third with around a million three hundred and twenty five thousand troops.

The United Kingdom has a fraction of these serving, over two hundred thousand. Size as such matters to some extent in the military, the kind of equipment being used, the level of training and the morale of the troops are equally if not more so important. Many countries also depend on reserves in times of war, and many on conscription, both of these are considered less professional then regular forces.