Platelets, also known as thrombocytes, are small, disc-shaped cell fragments in the blood that play a crucial role in the body's ability to stop bleeding. They are produced in the bone marrow from larger cells called megakaryocytes. When a blood vessel is injured, platelets quickly gather at the site, sticking to the damaged area and each other to form a temporary plug. In addition to their role in clotting, platelets release chemical signals that help attract more platelets and promote healing. They typically live for about 7 to 10 days in the bloodstream before being removed by the spleen or liver.