Varicose veins are enlarged, twisted veins that often appear blue or dark purple. They usually occur in the legs and can cause discomfort, pain, or aching. Varicose veins happen when the valves in the veins weaken, causing blood to pool and the veins to swell. Dr. K. Srikanth, Consultant - Vascular Surgeon, discusses varicose veins symptoms and complications, emphasizing pain, swelling, and potential skin changes, such as ulcers or blood clots, associated with this condition.