A keloid scar is a type of raised, thickened, and often excessively enlarged scar that can develop at the site of a wound, injury, surgical incision, or even minor skin irritation. Unlike normal scars, which typically become less noticeable over time and may flatten, keloid scars grow beyond the boundaries of the original injury or incision and can become larger than the wound itself. They are characterized by their raised and sometimes lumpy or ridged appearance.

Key characteristics of keloid scars include:

1. Raised and Elevated: Keloids protrude above the skin's surface and often have a firm, rubbery texture.

2. Reddish or Pinkish Color: They are typically red, pink, or darker than the surrounding skin, although their color can fade over time.

3. Growth Over Time: Keloids tend to continue growing for weeks or months after the initial injury, surgery, or inflammation, and they can become quite large.

4. Itching and Discomfort: Keloid scars are often associated with itching, tenderness, and discomfort.

5. Potential to Spread: Keloids can extend beyond the boundaries of the original wound or incision, and they may invade healthy skin nearby.

Keloid formation is thought to be related to an overproduction of collagen during the wound healing process. It is more common in individuals with darker skin tones and can occur anywhere on the body. Common sites for keloid development include the chest, shoulders, upper back, earlobes, and areas with a lot of tension or movement.

Keloids are considered a benign skin condition and do not pose a significant health risk. However, they can be cosmetically bothersome and cause discomfort or itchiness. Treatment options, as discussed in a previous response, are available to help reduce the appearance and symptoms of keloid scars, but it's important to note that keloids can be challenging to treat, and recurrence is possible.