The chin-up is a back exercise that mainly works the lats, some smaller muscles in the back, biceps, and forearms. This exercise can be included in a workout for the specific goals of back or arm development.
To perform this exercise you hold onto a bar in a dead hang. Your palms must face you and your grip should be about shoulder width on the bar. You then pull yourself up until your chin is above the bar.
This exercise should not be confused with the pull-up. The difference is that in this exercise the hand grip on the bar is narrower, and the palms are facing you. This exercise also involves more bicep action.