A normal scar takes 1-2 years to completely heal, or mature. It is usually red for the first 4-8 months, then it darkens slightly, followed by lightening after the first year. Scars are often initially raised, and then flatten with time. How a scar heals depends most of all on how your wound was closed by the surgeon. Other contributing factors include your genetics, and what happened to the scar after the surgery (e.g. infection, stress on the incision, etc). Abnormal scarring is quite common. Raised, red and unsightly scars are termed hypertrophic scars. Scars that grow outside the border of the original wound are termed keloid scars.