A boil, also known as a furuncle, is a painful, pus-filled bump that results from a bacterial infection of the hair follicle. It is a common skin infection, typically caused by a bacteria called Staphylococcus aureus. The infection usually starts as a tender, pinkish-red, bump which fills with pus- becoming larger and more painful. The boil can rupture and subsequently drain. Treatment options include warm compresses, incision and drainage, as well as topical and/or oral antibiotics.