A battalion is a military unit, typically consisting of 300 to 1,000 soldiers commanded by a lieutenant colonel, and subdivided into a number of companies (usually each commanded by a major or a captain). The typical battalion built from: 3 operational companies , one weapons company and one HQ company. In some countries, battalions are exclusively infantry, while in others battalions are unit-level organizations.

The word battalion came into the English language in the 16th century from the French language (French: bataillon meaning "battle squadron"; Italian: battaglione meaning the same thing; derived from the Vulgar Latin word battalia meaning "battle" and from the Latin word battuere meaning "to beat" or "to strike"). The first use of the word in English was in the 1580s.