Flat warts are benign growths caused by human papillomavirus (HPV) infection of the skin and mucous membranes, which are contagious and can be transmitted through direct or indirect contact. HPV can be transmitted through direct or indirect contact. When the skin surface is broken, HPV will invade the epithelial cells through the broken area, causing the epithelial cells to abnormally proliferate and differentiate, and warts will appear on the skin. Flat warts appear suddenly as slightly raised, flat papules that are usually small, round or oval in shape. Therefore, if the skin is in direct contact with the affected area of a person with flat warts, or if you touch the skin with your hands and then touch other parts of the skin with warts, it may lead to the spread of flat warts in yourself, and also sharing towels and other personal belongings with the patient can also lead to the spread of flat warts, which makes flat warts highly contagious. If you have flat warts, please go to the regular hospital in time to prevent infection.