In the military, firearms are categorized into "heavy" and "light" weapons regarding their portability by foot soldiers. Light firearms are those that can be readily carried by individual infantrymen (i.e. "man-portable"), though they might still require multiple individuals (crew-served) to achieve optimal operational capacity. Heavy firearms are those that are too large and heavy to be transported on foot, or too unstable against recoil, and thus require the support of a weapons platform (e.g. a fixed mount, wheeled carriage, vehicle, aircraft or water vessel) to be tactically mobile or useful.