What is a scab?

A scab is a dry, hard protective covering that forms over a wound or sore on the skin during the healing process. The scab is made of dried blood, serum, and other bodily fluids that have hardened and mixed together with dead skin cells. Scabs form a barrier that helps protect the wound from bacteria and further infection while new skin cells grow underneath. The color of a scab can range from brown to black to yellow, depending on the stage of healing. It is important not to pick at a scab as it can disrupt the healing process and lead to scarring.