An abscess is a localized collection of pus that can occur in any part of the body. It is caused by an infection and is characterized by redness, swelling, and pain. PIMPLE, BOIL, ULCER, GUMBOIL, STYE, CARBUNCLE, and SORE are all terms used to describe different types of abscesses. A PIMPLE is a small, inflamed bump on the skin that is filled with pus. A BOIL is a deep, painful infection of the skin and underlying tissue. An ULCER is an open SORE that is usually found on the skin or mucous membrane. A GUMBOIL is an abscess that occurs in the gums. A STYE is an infection of the eyelid that is caused by bacteria. A CARBUNCLE is a cluster of boils that form a connected area of infection. A SORE is an open wound or lesion on the skin.