The exercise performed by hanging from a bar with the palms facing away and pulling the chin above it is a pull-up. It is a closed-chain, upper-body pulling movement in which the hands stay fixed while the body moves.
A conventional pull-up uses a pronated, or overhand, grip. The athlete begins from a hang, pulls the body upward by bending the elbows and drawing the shoulders down and back, and finishes with the chin above the bar. A controlled return to the starting position completes the repetition.
Pull-ups mainly train the latissimus dorsi, while also involving the biceps, forearms, trapezius, rhomboids, and muscles that stabilize the trunk. Grip width, range of motion, tempo, and added weight can change the challenge.
The most common mix-up is with a chin-up. In the usual modern distinction, a chin-up uses a supinated, or underhand, grip with the palms facing toward the exerciser. Terminology varies in some training communities, but “pull-up” is the standard answer for the palms-away version described here.