Scar tissue forms as skin heals after injury . The amount of scarring may be determined by the wound size, depth, and location; the person's age; heredity; and skin characteristics including color (pigmentation).

Scar tissue is not identical to the tissue that it replaces and is usually of inferior functional quality. For example, scars in the skin are less resistant to ultraviolet radiation and sweat glands and hair follicles do not grow back within scar tissue.

The redness that often follows an injury to the skin is not a scar, and is generally not permanent. The time it takes for it to go away may, however, range from a few days to, in some serious and rare cases, a few years. Various treatments can speed up the process in serious cases. Scars form differently based on the location of the injury on the body and the age of the person who was injured. To mend the damage, the body has to lay down new collagen fibers.  In wounded tissue these fibers are over expressed with collagen, but not so in non wounded tissue. Stable forms of topical vitamin C have been shown to improve collagen formation.

Silicone scar treatments improve scar appearance and are often used to prevent and treat hypertrophic scarring. The exact mechanism of action is unknown though some studies suggest a manipulation of local ionic charges or a decrease in production of “pro-inflammatory” substances like TGF.

Dimethicone silicone gel appears to be is as effective as silicone sheeting in improving scar appearance.