The scab usually appears at the wound site, and its main component is actually the blood flowing from the broken blood vessels in the wound, as well as the substance in the exudate from the wound site, which clots and adheres to the wound surface and is called a scab. If the wound is dry and there is no inflammation, it will soon form a scab, which serves to protect the wound. The scab usually falls off naturally in 1-2 weeks because the wound underneath the scab is gradually shrinking and the scab and the skin will have no adhesion after the shrinkage, so the scab will fall off. The whole process can be divided into two steps: 1. the granulation tissue at the wound area proliferates, the granulation tissue at the wound area grows out from the side and bottom of the wound to fill the wound; 2. after filling the wound, the fibroblasts produce a large number of collagen fibers, which further wraps the granulation tissue under the skin, and a large number of fibers are formed thus appearing as a scar at the wound area. It is important to note that if there are more hair follicles and sweat glands in the injured area, they cannot be completely regenerated.