Varicose veins are visible, protruding veins that appear just under the skin. The word "varicose" comes from the Latin root varix for "twisted." The veins may occur in clusters that look like spider webs. They may also be large, single veins that are easily visible. They're most often seen on people's legs, especially their calves, and are made up of stretched, expanded, or twisted veins. The blood flow in these veins has been slowed down or reversed.
Between 10% and 20% of the population has some form of varicose veins. They appear between the ages of 30 and 70, and they usually get worse with age.
Varicose veins occur 2 to 3 times more often in women than in men. It is estimated that 50% of people with varicose veins have a family history of the condition.