HPV is short for human papillomavirus, a very common sexually transmitted infection divided into different types, each identified with a number. High-risk HPVs (HPV 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, 66, and 68) can cause several types of cancer. Two of these, HPV16 and HPV18, are responsible for most HPV-related cancers. Low-risk HPVs are mostly asymptomatic. Sometimes, they may cause warts on or around the genitals, anus, mouth, or throat.