A claw hammer is composed of a metal head and a handle, which historically was made of wood but also may be of steel, fiberglass, or other composite. One side of the head has a poll with either a smooth or textured surface and is used for driving, while the other is formed into a pair of downward curving V-shaped claws and used for prying — most commonly removing nails from wood. The greater the curve of the claw, and longer the handle, the greater the leverage that may be applied.

Source: Wikipedia