Spider veins are small, thin blood vessels that appear close to the surface of the skin. They often look like red, blue, or purple lines and can resemble a spider's web, hence the name. These veins are commonly found on the legs and face and are usually harmless, though they can sometimes cause discomfort. The development of spider veins can be influenced by various factors, including genetics, hormonal changes, and prolonged standing or sitting. While they are not a serious medical condition, some people may choose to seek treatment for cosmetic reasons or to alleviate any associated symptoms.