A wing is a level of command below higher headquarters. It has a distinct mission with significant scope and is usually composed of a primary mission group (e.g., operations, training) and the necessary supporting groups. By pulling together the mission and support elements, a wing provides a significant capability under a single commander. It is often responsible for maintaining the installation. A wing has several squadrons in more than one dependent group. A wing may be either an operational wing, an air base wing, or a specialized mission wing.