Cervical cancer is the second most common cancer among women worldwide, with an annual incidence of approximately half a million cases. Over 80% of these occur in developing countries. It is firmly established that persistent infection with one of the so-called high-risk human papillomavirus (hrHPV) types is a prerequisite for the development of cervical cancer. Estimating the impact of HPV vaccination on the reduction in the rate of cervical cancer requires an understanding of the determinants that govern the prevalence of the various hrHPV types prior to vaccination. The fact that hrHPV is sexually transmitted partly explains the age-specific patterns in hrHPV prevalence data and the geographic variation in hrHPV infection risk. However, it is unclear why some high-risk types are more widespread than others.