A coagulation, also known as clot is a semi-solid substance that blood forms, especially when it is in air. When a person bleeds, the blood turns into a clot at the injury.
A blood clot is also called a thrombus. The process is called coagulation.
If a person gets a cut on their body, that person may bleed. To stop the bleeding, the human body does several things. First, the brain orders the liver to produce chemicals that will help the clot to form. When the chemicals released by the liver arrive at the injury, the coagulation begins. In the mean time, the brain also lessens the blood flow near the injury (by tightening the veins and arteries in that area), so that not as much blood is lost.
There is a limit to how quickly a clot can form. If the cut is very deep and the person bleeds too much, a clot may not be able to form and a lot of blood may be lost.