Whiteheads form when bacteria clogs a hair follicle, but the surface of the follicle remains closed. Because of the closed surface, it appears as a white bump. If the follicle's surface were open, then it would be a blackhead—because the clogged material would oxidize and turn dark. Whiteheads are the most tempting of acne types to pop. And it will likely be useless to tell you not to pop. So if you do pop, make sure your hands are clean and that you cleanse before and after popping. Overall, though, it's best to focus on using the right treatments for whitehead prone areas rather than hunting for individual whiteheads.