HPV infection is one of the most common sexually transmitted infections (STIs), and both carriers and patients of HPV are the main sources of infection. HPV is highly infectious and is most often transmitted by direct or indirect sexual contact, and can be transmitted to others before warts are produced or without obvious symptoms (so-called subclinical infection). In addition, close contact, skin abrasions, the birth of a baby through the mother’s HPV-infected birth canal, self-inoculation (transmission to other parts of the body through scratching), and contaminant transmission are also relatively common indirect routes of transmission. The prevalence of HPV infection depends mainly on the age and sexual habits of the population. Domestic and international studies have found that HPV infection rates are highest among sexually active young women, with a peak age of 18-28 years, and decline significantly with age. Risk factors for HPV infection include: 1. multiple sexual partners; 2. too frequent sex; 3. early sexual initiation (before the age of 16); 4. unprotected sexual contact; 5. other sexually transmitted diseases in oneself or in the other party; 6. low immune function of the body due to tumors, autoimmune system diseases, organ transplants, AIDS or other reasons.