A pull-up is a compound exercise that works the entire upper body, primarily the back.
The exercise is performed when hanging from a bar with the hands in an overhand position. The body is then pulled up through the air until the chin clears the bar. This is similar to a chin-up, which is performed with the hands in an underhand position, though chin-ups use a little more of the biceps and less of the back.
Pull-ups require considerable strength, and are great at both increasing muscle mass and burning fat .