Each pore is an opening to a follicle, which contains a hair and an oil gland. These oil glands help lubricate
the skin and help remove old skin cells.
When glands produce too much oil, the pores can become blocked. Dirt, debris, bacteria, and inflammatory
cells build up. The blockage is called a plug or comedone.
The top of the plug may be white (whitehead) or dark (blackhead).
If the plug breaks open, the material inside causes swelling and red bumps to form.
If the inflammation is deep in your skin, the pimples may enlarge to form firm, painful cysts.