This document discusses several sexually transmitted infections (STIs) including gonorrhea, chlamydia, syphilis, and HIV/AIDS. It describes the causative organisms, sites of infection, clinical features, complications, diagnosis, treatment and follow up care for each STI. Gonorrhea is caused by Neisseria gonorrhoeae and commonly infects the genitourinary tract. Chlamydia trachomatis causes chlamydia which often presents asymptomatically. Syphilis is caused by Treponema pallidum and progresses through primary, secondary, latent, and tertiary stages if left untreated. HIV/AIDS spreads through sexual contact, blood, and perin