Scars are zones of sinewy tissue (fibrosis) that supplant ordinary skin after damage. A scar comes about because of the natural procedure of twisted repair in the skin and different tissues of the body. In this manner, scarring is a characteristic part of the recuperating procedure. Except for extremely minor injuries, each twisted (e.g., after mischance, infection, or surgery) brings about some level of scarring. A special case to this are creatures with complete recovery, which regrow tissue without scar development.

Scar tissue is made out of the same protein (collagen) as the tissue that it replaces, yet the fiber creation of the protein is distinctive; rather than an arbitrary basketweave development of the collagen filaments found in typical tissue, in fibrosis the collagen cross-connections and structures a maintained arrangement in a solitary direction.[1] This collagen scar tissue arrangement is more often than not of second rate useful quality to the ordinary collagen randomized arrangement. For instance, scars in the skin are less impervious to bright radiation, and sweat organs and hair follicles don't become back inside scar tissues.[2] A myocardial dead tissue, usually known as a heart assault, causes scar development in the heart muscle, which prompts loss of solid force and potentially heart disappointment. Be that as it may, there are a few tissues (e.g. bone) that can recuperate with no auxiliary or practical disintegration.

All scarring is made out of the same collagen as the tissue it has supplanted, yet the sythesis of the scar tissue, contrasted with the typical tissue, is different.[1] Scars vary from different scars in the measures of collagen overexpressed. Names have been connected to the distinctions in overexpression. Two of the most widely recognized sorts are hypertrophic and keloid scarring,[3] both of which experience inordinate firm collagen packaged development overextending the tissue, closing off recovery of tissues. Another structure is atrophic scarring (depressed scarring), which likewise has an overexpression of collagen blocking recovery. This scar sort is depressed, in light of the fact that the collagen groups don't overextend the tissue.Stretch imprints (striae) are viewed as scars by a few.

An atrophic scar appears as a depressed break in the skin, which has a hollowed appearance. These are brought about when hidden structures supporting the skin, for example, fat or muscle, are lost. This kind of scarring is frequently connected with acne,[8][9] chickenpox, different illnesses (particularly Staphylococcus disease), surgery, or mischances.