Skin swelling is a common medical condition that can be caused by a variety of factors, such as allergies, infections, and autoimmune disorders. It is characterized by an abnormal enlargement of the skin, which can manifest in different ways. The most common forms of skin swelling are blisters, weals, wheals, and pustules. Blisters are small pockets of fluid that form on the skin, usually due to friction or burns. Weals are raised, red, itchy areas of skin that can be caused by an allergic reaction. Wheals are similar to weals, but they are larger and more raised. Pustules are small bumps filled with pus, which are usually caused by bacterial or fungal infections.