A platelet, also known as a thrombocyte, is a small cell fragment that plays an important role in blood clotting and wound healing. Platelets are produced in the bone marrow and circulate in the bloodstream. When there is an injury to a blood vessel, platelets become activated and stick together, forming a plug to prevent blood loss. They also release chemicals that help in the formation of a clot to seal the damaged area. In summary, platelets are essential for maintaining hemostasis (blood clotting) and healing injuries.