Platelet activation is a crucial process in the body's response to injury. When a blood vessel is damaged, platelets, which are small cell fragments in the blood, quickly adhere to the site of injury. This adhesion is triggered by exposure to collagen and other substances in the damaged tissue. Once adhered, the platelets undergo a transformation, becoming activated. They change shape, release chemical signals, and attract more platelets to the site. This aggregation forms a temporary plug that helps stop bleeding and initiates the healing process, ultimately leading to the formation of a stable blood clot.