What are acne scars?

Acne scars are the marks left on your skin after acne has healed. Typically, scarring happens when the skin tries to heal inflammation caused by active acne before the acne has gone away. Collagen loss and tissue damage during the acne healing process contribute to scar formation. Scarring can also be caused by exposure to the sun, repeated acne in the same area, or skin habits like picking or popping pimples.