Oh pustules, how I loathe thee! They are categorized as inflammatory pimples. A pustule occurs when the bacteria from the dead skin cells and oils in your pores attract other strains of bacteria.
Whiteheads are probably the easiest type of pimple to get rid of, but blackheads can be a little trickier. Blackheads are non-inflammatory, open comedones. The open pore allows air to get in. The air oxidizes all the dirt and oils trapped in your pore, therefore creating that black appearance.
Whiteheads are one of the most common types of pimples. They are categorized as non-inflammatory comedones. This just means that they are clogged hair follicles, and the surrounding skin is not raised or red.