Bruises form when small veins and capillaries break under the skin.  Red blood cells leak out of these blood vessels, collect under your skin and therefore cause that bluish, purplish, reddish, or blackish mark.  Bruises go through several changes in color as the body begins to repair itself.  The color changes mean that your body is metabolizing (breaking down) the blood cells in the skin.  Skin bruising can sometimes be slow to heal and can last for several weeks before resolving.  This can impede on your ability to return to work or social activities.  Cosmetic injectable procedures to the face, such as filler injections are often associated with bruising.