A Training squadron was a starfighter squadron that had been formed from cadets who had passed though initial pilot training, but were not yet ready for active combat service. Training squadrons were typically made up of the same roster of beings that, ideally, would form the actual combat unit when the squadron was activated. Once compiled, the members of such squadrons would learn more advanced maneuvers for their chosen craft, battle tactics suited to flying with a group in order to get acquainted with each other's flying styles and personalities, as well as to learn different aspects of the fighter pilot trade.
Training squadrons within the Alliance to Restore the Republic, and later within the New Republic's Starfighter Command, would be led and trained under respected combat veterans. As circumstances dictated, older, more experienced and battle-tested pilots would be pulled from their line units and given command of training units, leading them during exercises, maintaining discipline, and, eventually, reporting on their readiness for frontline service. Once the unit was activated, it would be considered an operational squadron in and of itself, its members active-duty pilots. This was in keeping with established Alliance and New Republic training theories.
In 6 ABY, during its reorganization, Rogue Squadron temporarily held the designation of a training squadron. During this time, the Y-wings of Aggressor Wing were also retrained and reformed, becoming Defender Wing under the command of General Horton Salm.