Many people can do a pullup or a chinnup with nothing but their bodyweight. And it is hardly considered a feat of strength to do so. But there are many variations that are.

First off let me preface this by saying that pullups are done with the palms facing away from you. Chinnups are done with the palms facing toward you. Of course, there are other methods like a mixed grip or parallel grip as pictured to the side here.

Chinnups are easier than pullups because of the way the bicep wraps around the forearm. Usually people can do about 20-30% more reps or weight in the chin.

Weighted pullups are one method. When you can lift half your bodyweight as added weight you are really getting somewhere. It can be done with a weight vest, hanging from a belt or even your feet.