HPV stands for human papillomavirus, which refers to any of a group of more than 100 related viruses that infect humans and can cause warts. Different types of HPV infect different parts of the body: the hands, the feet, the mouth, the upper respiratory tract, or the genital region. Wherever an HPV infection occurs, it may cause abnormal growths (warts or other lesions) or it may cause no obvious symptoms.

There are around 30 types of HPV that infect the genitals. Some of these cause genital warts that may affect the vulva, vagina, and cervix in women; the penis and scrotum in men; and the anus in both sexes. These types are called low-risk HPV. Other types of HPV that infect the genitals are called high-risk HPV because while they tend not to cause obvious symptoms, they can eventually lead to cancers of the anogenital area. Almost all cases of cervical cancer are associated with a high-risk HPV infection.

HPV infections are very common. The Centers for Disease Control and Prevention estimates that at least 50% of people who have had sex will have HPV at some time in their lives. The CDC also estimates that 20-25 million Americans have an active HPV infection at any one time. Most of these people will not get cancer from their HPV infection.