Bending the arm to lift a weight toward the shoulder, working the biceps, is called a biceps curl.
A curl is an elbow-flexion exercise: the forearm moves toward the upper arm while the weight travels toward the shoulder. A typical repetition begins with the arm extended and ends with the elbow flexed, then the weight is lowered under control. The biceps brachii is a major target, but the brachialis and brachioradialis also help bend the elbow.
Grip changes alter the emphasis. With palms facing upward, the biceps brachii can contribute strongly; a neutral “hammer” grip gives the brachioradialis a larger role, while a palms-down reverse curl places more demand on the forearm muscles. Dumbbells, barbells, cables, and resistance bands can all be used.
A curl is different from an extension: curls bend the elbow, while extensions straighten it. A raise usually moves an arm at the shoulder, and a press pushes a weight away rather than drawing it toward the body. Swinging the torso to move a heavy weight reduces the exercise’s isolation and can increase injury risk.