1) Acne appears as white or red bumps that are painful to touch.
2) Whiteheads are formed due to trapped oil and debris within the hair follicles of the skin.
3) If whiteheads are formed in the deeper layers, a soft, fluctuant mass called a cyst appears.
4) Blackheads are open and dark in color. This is due to melanin pigment and not dirt.
5) The plugged wall of the follicle ruptures on to the skin surface, and can get infected by bacteria and form pimples or "zits".
6) Small red bumps are called papules. Larger red bumps are called nodules.
7) A pustule is a whitish yellow squeezable spot due to the accumulation of pus inside. After the lesions heal, they leave behind scars that form permanent marks on the skin.