Sexually transmitted infections (STIs) are infections that can be transmitted through sexual contact or orally. Common STIs include chlamydia, gonorrhea, genital herpes, HIV/AIDS, and syphilis. STIs can cause permanent damage if left untreated, such as infertility or pelvic inflammatory disease. While some STIs have symptoms, others do not, so annual screening is recommended. STIs are prevented through abstinence, condom use, vaccination, limiting sexual partners, and getting tested annually.