Acne is a common skin condition that occurs when hair follicles become clogged with oil, dead skin cells, and bacteria. It typically presents as pimples, blackheads, whiteheads, or cysts on the face, neck, chest, back, or shoulders. Acne can vary in severity, ranging from mild outbreaks to more severe cases that may cause pain and scarring.

The main factors contributing to acne development are excess oil production, clogged pores, inflammation, and bacterial growth. Hormonal changes, certain medications, genetics, and lifestyle factors can also play a role in acne formation.

Acne scars are the visible marks or depressions that remain on the skin after acne lesions have healed. They are a result of the skin's healing process, where collagen fibers are disrupted or overproduced during the inflammatory response to acne.