Picture of Blood Clot
Blood clots are semi-solid clusters of blood elements called platelets and other blood proteins that form as the result of an injury to prevent blood loss. The physiological process that is responsible for the formation of blood clots is called coagulation. A blood clot may also be called a thrombus. Sometimes, blood clots form on the inside of blood vessels located in the heart or other parts of the body. Blood clots that break free and travel throughout the blood stream can potentially be very dangerous. A blood clot that breaks free and travels through the bloodstream is called an embolus.
Text: Reference: "Blood Clots." American Society of Hematology.