While sometimes it seems pimples appear overnight, the development of an acne breakout is actually anextended process that begins at the cellular level. Each follicle is connected to the
sebaceous glands; these glands secrete an oil substance know as sebum to lubricate your hair
and skin.

When your body produces an excess amount of sebum and dead skin cells, the two can build up in the hair follicle and together form a soft plug. The obstruction causes swelling of the follicle (causing white points) and the superior part of the obstruction can turn black (blackheads).

If the obstruction causes a rupture in the wall of the follicle; the dead cells of the skin, the fat
and the bacteria,found normally on the surface of the skin, can penetrate it and form small infected areas calls pustules (also known as pimples). All this is followed by an immoderate
inflammatory reaction.If these infected areas are deep within skin, they can increase in size
until forming a firm and painful cyst.