At first, you may mistake a boil for a zit because they’re both red, raised lumps. But there’s one key difference between the two skin lesions: boils are commonly caused by a bacterial infection from Staphylococcus aureus , also known as a staph infection, while pimples occur when oil, dead skin cells, and bacteria clogs your pores. Plus, boils are usually firm and painful to the touch. Boils aren’t just the only mysterious lumps on your skin—here are the explanations behind these 13 other skin mysteries . Staph is generally harmless bacteria that lives on the skin around the nose, mouth, genitals, and rectum. But it can cause an infection once it enters your skin through a cut or other wound. And thus, a boil will form. Ingrown hairs on the groin are extremely common sites for boils because the bacteria can infect the hair follicles—small openings in the skin where the hair grows. You’ll often find boils on moist areas of the body like the buttocks, thighs, groin, and armpits. Since...