In the military, a squadron is a small unit sent out from the main group to do some particular task. In the air force, for example, a squadron might fly out on a surveillance mission.
This word comes from the military, but the meaning varies depending on the branch. In the army, a squadron is a cavalry (horses) unit that has at least two troops, which are smaller collections of soldiers. The squadron also includes a headquarters and support. In the air force, a squadron has at least two flights, which are the equivalent of troops. An air force squadron is smaller than a group and bigger than a flight in the basic chain of command.