What is a boil ?
Generally its an infection of a hair follicle. This infection is caused by a bacteria called streptococcus aureas. Bacterias are all around is, the body needs normal bacteria to function properly.
Hair follicles that have been opened, either from scratching allow bacteria to penetrate. Upon penetration, the area becomes red and tender, over time it hardens and forms a yellow point. Mostly its pea sized.
This yellow point consists of bacteria fighting white blood cells, which the body releases to counter