A timing aid used when a behavior is too quick or fleeting to reward in the moment, or when it is not practical to deliver a treat while your dog is still in the position you have asked for. It is typically a verbal cue like "Yes!" or the sound of a clicker.

To condition a marker, repeatedly pair it immediately before a treat so your dog learns that the marker always predicts food. Once conditioned, the marker can be used as a precise signal that tells your dog exactly which behavior has earned a treat. It bridges the gap between the moment the behavior occurred and the time it takes you to deliver the reinforcement.