What is round part of a hammer?

The round part of a hammer is called the face or head. It is typically made of hardened steel and is used for striking nails or other objects. The face may be smooth or have a pattern to help grip the nail. A hammer with a smooth face is better for finishing work, while a hammer with a textured face is better for framing or rough carpentry. The face of a hammer can also be replaced if it becomes worn or damaged.