The Boil is also known by another name of furuncle. This is a sort of deep folliculitis and it is commonly known as the infection of the hair follicle. It is mainly caused by a sort of infection called the bacterium Staphylococcus aureus. As a result of this you can experience a painful swollen area which results on the skin due to puss and dead tissues.When the Boil gets clustered they form a kind of condition called carbuncles. These occur as bumpy red puss filled lumps and they are extremely tender, warm and at the same time immensely painful.