Varicose veins are enlarged veins extending down the leg, or occurring in bunches, like grapes, or in snakelike curves beneath the surface of the skin.  Varicose veins develop when valves in veins fail.  The distance from the feet to the heart is the furthest blood has to travel in the body. Consequently, if the vein valves fail, the backflow of blood causes the surface veins in legs to be under pressure, become swollen, enlarged and distorted.