My husband has a large boil on his groin area and another rather small one a few inches away what caused this?

BOIL: The medical term is furuncle; an infected ingrown hair. Hair follicles are connected to gland producing sweat & other substances that moisturize skin & defend against infection. When ingrown hairs can't reach the surface, they "plug the system", allowing substances to accumulate below the surface. A boil forms. Groin is a common site b/c the hairs are naturally curly & prone to become ingrown.