Scars form when the dermis (deep, thick layer of skin) is damaged. The body forms new collagen fibers (a naturally occurring protein in the body) to mend the damage, resulting in a scar. There are different kinds of scars. Most scars are flat and pale, however, in cases when the body produces too much collagen, scars can be raised. Some scars can have a sunken or pitted appearance, this kind of scarring occurs when underlying structures supporting the skin (for example, fat or muscle) is lost. Some surgical scars have this appearance, as do some scars from acne.