Target indicators, also known as target markers or TI's for short, were flares used by the RAF's Bomber Command during World War II. TIs were normally dropped by Pathfinders onto the target, providing an easily seen visual aiming point for the following "main force" of bombers to aim at. After their introduction, the use of TIs expanded to include en-route markers to gather up lost aircraft, additional TI drops to keep the target lit over long periods, and various changes in technique to address German defences.