Purpura (from Latin: purpura, meaning "purple") is the appearance of red or purple discolorations on the skin that do not blanch on applying pressure. They are caused by bleeding underneath the skin usually secondary to vasculitis or dietary deficiency of vitamin C (scurvy).
Purpura measure 0.3-1 cm (3-10 mm), whereas petechiae measure less than 3 mm, and ecchymoses greater than 1 cm.