The control flag marks the spot that is circled on the map. It is made of fabric hung on a triangular box-kite-like wire frame. Each of the three square cloth faces is made up of a white upper triangle and an orange lower triangle. In North America, th e flag is usually hung from a branch or piece of deadwood near the control site, while in Europe the flag is usually hung from a wooden framework or metal stake stuck in the ground.

Attached to or near the control flag are one or more punches and a card with the "control code". Each flag is assigned a unique control code, usually a two-letter combination (numbers may also be used, but international rules state that numbers 1-40 are not used for control codes). These codes allow the orienteer to determine that the control is in fact the correct one. The codes are usually listed in the clues that define the controls for each course, and many orienteers write the control codes in the corresponding boxes of the control card, to help make sure that they never punch at the wrong control or in the wrong box of the punch card.