The basic pimple is a plugged hair follicle. If this plugged follicle stays under the skin, it is called a whitehead. When it reaches the surface of the skin and opens up, it is called a blackhead because it looks black on the skin's surface.
Acne can be mild or severe. Mild outbreaks can usually be helped with over-the-counter (OTC) ointments or creams. Severe acne may require prescription ointments or antibiotics to stop the bacteria from forming.