In the case of a traumatic bruise, its color changes accordingly from the time it occurs to the time it heals, purple being the second of these stages. In the case of a purple bruise with no apparent cause, it may be a bleeding disorder. When a traumatic bruise first appears, it is usually red because the blood oozing out from under the skin is fresh and rich in oxygen; after a few hours or 1~2 days, the blood begins to be deprived of oxygen, and depending on the size, location, and severity of the bruise, it may appear blue, purple, or black. In life, you can take ice compresses, topical ointment, compress pressure, elevate the affected area and other methods to help eliminate the bruise. Purple bruises and blood clots that appear inexplicably on the skin are called purpura and purple spots, characterized by pressure without fading, and most often occur in school-age children. There are two common causes, one is thrombocytopenic purpura, characterized by thrombocytopenia leading to spontaneous bleeding of the skin and mucous membranes; the second is vascular purpura, characterized by platelets do not decrease, caused by infection, drugs, food, capillary allergic reactions. The second condition requires timely medical examination, and may develop into an irreversible and serious disease if not treated in time.