An abscess is a pocket of pus. You can get an abscess almost anywhere in your body. When an area becomes infected, your body's immune system tries to fight it. White blood cells go to the infected area, collect within the damaged tissue and cause inflammation. During this process, pus forms. Pus is the buildup of fluid, living and dead white blood cells, dead tissue and bacteria or other foreign substances. Bacteria, viruses, parasites and swallowed objects can all lead to abscesses. Skin abscesses are easy to detect. They are red, raised and painful. Abscesses inside your body may not be obvious and can damage organs, including the brain, lungs and others. Treatments include drainage and antibiotics.