An abscess occurs when there is a bacterial infection. It can also happen if the oil or sweat gland in the skin becomes blocked. The most common areas of the body where an abscess is found are the underarms, hands and feet, genitals, trunk and buttock area.
When an infection occurs, the body's immune system goes into action in the form of white blood cells that are sent to the affected area to fight the bacteria. As this battle is taking place, some tissues lying nearby die, which leaves a hole filled with pus-forming an abscess. The pus contains bacteria, white blood cells and dead tissues.