Vein

A vein is a type of blood vessel that carries blood back to the heart from different parts of the body. Unlike arteries, which carry oxygen-rich blood away from the heart, veins generally transport blood that is lower in oxygen. Veins have valves that prevent blood from flowing backward, helping it return smoothly to the heart, even against gravity. They are essential components of the circulatory system, ensuring that blood is properly circulated and waste products are removed from tissues. Veins are located throughout the body, including visible superficial veins on the skin's surface.