A blood clot is a clump of blood that has changed from a liquid to a gel-like or semisolid state. Clotting is a necessary process that can prevent you from losing too much blood in certain instances, such as when you’re injured or cut. When a clot forms inside one of your veins, it won’t always dissolve on its own.


Source: https://www.healthline.com/health/how-to-tell-if-you-have-a-blood-clot