Ice pick scars are deep pits that are usually less than 2mm across. They extend into the skin, giving the skin an appearance of having been punctured by an ice pick.
Boxcar scars are angular scars with sharp vertical edges, and resemble the scars left by chicken pox. They may be shallow or deep, and are most often found on the cheeks and temples.
Rolling scars are caused by damage under the surface of the skin. They give the skin a wave-like appearance. They tend to be wide and shallow.
Hypertrophic scars are raised and lumpy. They tend to appear on the back and chest, but can also appear on the neck and face. Often the result of severe acne (cysts or nodules), they generally stay within the boundary of the original wound, and may decrease in size over time.
Hyperpigmentation refers to the red or dark marks that are left behind after a pimple heals. These marks, also called macules, are not scars, but are often confused with scars because they can last for months or even years before they fade.