Sexually transmitted infections (STIs), also known as sexually transmitted diseases (STDs) or venereal diseases, are infections transmitted through sexual contact. Common STIs include syphilis, gonorrhea, chlamydia, herpes, hepatitis C and hepatitis B, human papillomavirus, and HIV. Although great advances have been made in the prevention, detection, and treatment of STIs, these infections remain a common problem in the United States. “Safe sex” practices, such as using condoms, avoiding sexual contact while using alcohol or drugs, and limiting the number of sexual partners, can prevent STIs. The USPSTF wanted to determine whether counseling about safe sex during primary care doctor visits would be an effective way to decrease STIs in the United States.