This document discusses sexually transmitted infections (STIs), including that over 25 STIs can be passed through sexual contact, with bacterial STIs often curable but viral STIs not curable. It notes that the US has the highest STI rates among industrialized nations and discusses factors that contribute to STI transmission like early sexual initiation, multiple partners, and inconsistent condom use. The document outlines principal bacterial and viral STIs like chlamydia, gonorrhea, HPV and herpes. It also discusses the disparate impact of STIs and increased susceptibility among women.