Urticaria is the medical name for hives. Hives are itchy, raised, red areas of skin which range in shape and size. They can be a few millimeters to a few inches in diameter. They can form in rings, patches, or in round circles.
Welts (red lesions with a flare at the borders) are one manifestation of hives. Hives can occur anywhere on the body, and are very common the arms, legs, and trunk of the body.
