Acne is considered the most common skin condition and a long-term one. It occurs when hair follicles get clogged up with dead skin cells and oil (sebum). The condition is most common in teenagers but anyone can be affected. Acne is characterized by whiteheads, blackheads, nodules and pimples. While it is not dangerous, it can result in infection and scarring. All causes, forms and treatments for acne are discussed here.