The venous system is the part of the circulatory system that returns de-oxygenated blood through veins back to the heart and through the lungs to be recirculated with oxygen rich blood. When a disease occurs in the veins, it is called venous disease.
 

Varicose veins, or enlarged and twisted rope-like veins that appear near the surface of the skin, are a result of venous disease. They are most commonly found in the legs and ankles because standing and sitting without movement increases pressure in the lower extremities, and are a result of faulty valves higher up in the leg.