A black-and-blue mark, medically called a contusion or an ecchymosis, is typically the result of a blunt impact that doesn’t break the skin but causes tiny blood vessels to break and leak blood into the surrounding tissues.
Your body responds to this with a variety of factors that cause clotting to halt the bleeding. You’re left with an unsightly and sometimes tender bruise. Over several days or a few weeks, white blood cells will consume the clot, causing your bruise to turn an array of colors, ranging from purplish to green to yellow, and then eventually fade away. Bruises can be attributed to several factors. Here are six.