Acne is an infection of the skin, caused by changes in the sebaceous glands.
The sebaceous glands secrete an oily substance called sebum which
function is to protect and waterproof hair and skin, and keep them from
becoming dry. If too much sebum is produced, it is common that oils from
the glands combine with dead skin cells to block hair follicles. Under
the blocked pore, oil builds up. Skin bacteria can then grow very
quickly. This infection makes the skin become swollen and red, which
becomes visible. The redness comes from the inflammation of the skin in
response to the infection.
While the most common form of acne is called acne vulgaris, which
means common acne, there are also other types of acne and acne-related
skin diseases like:
Acne fulminans
Acne medicamentosa
Chloracne
Rosacea
The most common places for acne to happen are: face, back, chest and shoulders.
Acne is most common during adolescence, affecting more than 85% of
teenagers. For most people acne diminishes over time, but it is
impossible to predict how long it will take to disappear entirely. Some
individuals will continue to suffer well into their thirties and
beyond.
The most common effects that acne can cause are:
Scars
Skin becomes more sensitive and painful to physical contact
Reduced self-esteem, which can cause depression.
Acne lesions are commonly referred to as pimples, zits, spots, or acne.
References:
http://en.wikipedia.org/wiki/Acne_vulgaris
http://simple.wikipedia.org/wiki/Acne
http://simple.wikipedia.org/wiki/Sebaceous_gland