What are varicose veins?

Vein with weak walls. Dr. Nielsen has given a very nice answer. The other part of the problem is that varicose veins also have weak walls. This allows the high pressure in the veins to stretch the veins, make them bigger and longer, and that causes the large, bulging, squiggley appearance of the veins.
Bulging veins. Varicose veins are bulging veins that are formed when veins are exposed to increased pressure. The increased pressure in the vein is usually due to leaky vein valves that allow the blood to pool and pressurize veins. Varicose veins may be entirely asymptomatic or cause pain, swelling, tiredness, or heaviness of the legs.
Bulging veins. Varicose veins are enlarged usually twisting blue veins larger than 3 mm in diameter. Veins return blood to the heart. One-way valves are present in most veins to keep blood from flowing back down the vein. In varicose veins, these valves don't work well (either because the vein walls have stretched or because the valves are dysfunctional)- resulting in blood pooling in the veins.
Varicose Veins. Varicose veins are disease veins have become large, bulging, with serpentine-like shape. They are often painful and unsightly & usually form on the legs. They occur due to a disease process witin the veins in which the valves that direct blood flow become damaged thus allowing stagnation of blood flow & pressure build-up inside them. The valve damage is usually progressive & it worsens w/ time.
Varicose veins. Veins that bulge under the skin secondary to abnormal flow and valves that are damaged. Commonly they can cause pain, swelling, bulging, aching, phlebitis or even skin changes or open sores. There are many minimally invasive options nowadays for treatment based on the size and symptoms you have. For this you can see a vein specialist about medical compression therapy and options for your specifics.
Big Weak Leaky Veins. Varicose veins are enlarged often several times larger than normal veins because their walls are weak which causes them to dilate. They are incompetent because the valves inside of them leak so they dont circulate the blood effectively. They usually occur on the legs.
Bulging Veins. Varicose veins are bulging grape-like appearing veins which are most commonly seen on the legs. These are due to leaking (refluxing) valves usually in the saphenous system. Some causes include hereditary, pregnancy, trauma and aging. The gold standard of treatment is to have a venous reflux ultrasound to both diagnose and form a treatment plan. You should see a vein specialist.
Enlarged veins. Varicose veins are swollen, twisted, and sometimes painful veins that have filled with an abnormal collection of blood.