The chin-up is a strength training exercise,it hits your lats and biceps.You must not confuse a chin-up with a pull-up.When doing a chin-up the palms are facing towards you unlike the pull-up where the palms are facing away from you.
How to do a Chin-up1.Extend your arms above your head and grab the bar or the gymnastic rings.Make sure to get a good grip with the bar.
2.Pull yourself towards the bar until your chin is over the bar and you are touching the bar with your chest.If you can't pull yourself over the bar do not try to extend your neck,start by doing negatives and you will get there eventually. (A negative chin-up is when you jump over the bar and then lower yourself slowly, this way you can build the necessary strength which is required to do a chin-up).
3.Lower yourself at the starting position and repeat.
You can even kip when doing a chin-up but this would make the exercise less effective and would build less upper body muscle although it would improve your total body strength.