Beneath the pores of our skin are follicles, which host a hair and an oil gland. The oil gland releases oil (sebum), which travels out of the pore and onto the skin via the hair. This layering of oil helps keep skin moisturised. Old skin cells are also shed from the follicles through the pores.
Acne occurs when the pores of your skin become blocked with oil, dead skin, or bacteria. This usually happens in individuals whose follicles produce excessive oil.
Acne can manifest as black heads, white heads, inflamed papules or pus-filled pustules (pimples). Inflamed papules and pimples can lead to scarring (see below).