IDF, Army Of Israel

In several countries the army is officially called the land army to differentiate it from an air force called the air army, notably France. In such countries, the word "army" on its own retains its connotation of a land force in common usage. The current largest army in the world, by number of active troops, is the People's Liberation Army of China with 2,250,000 active troops and 800,000 reserve personnel followed by the Indian Army with 1,325,000 active troops and 2,142,821 reserve personnel.
By definition, irregular military is understood in contrast to regular armies which grew slowly from personal bodyguards or elite militia.