Acne is a term for plugged pores (blackheads and whiteheads), pimples and even deeper lumps (csyts or nodules) that occur on the face, neck, chest, back, shoulders and even the upper arms. Acne affects most teenagers to some extent. However, the disease is not restricted to any age group; adults in their 20's - even into their 40's - can get acne. While not a life threatening condition, acne can be upsetting and disfiguring. When severe, acne can lead to serious and permanent scarring. Even less severe cases can lead to scarring.

- The American Academy of Dermatology

Types of acne 

Acne lesions range in severity, and are divided into two categories. Non- inflammatory lesions and Inflammatory lesions. (A lesion is a change in the structure of the body's tissue and could be external like a cut, or internal like an ulcer )