The human papillomaviruses (HPVs) are a large group of viruses, about 40 of which can infect the human genital tract. Some HPVs are known to cause cervical cancers, while others cause genital warts. Most genital HPV infections go away on their own, but when they become chronic, they can cause precancerous and cancerous changes in the cells that line the uterine cervix. Over 90% of cervical cancers are caused by HPV infection.