Ans. Some common sexually transmitted diseases include:- Chlamydia: Caused by the bacterium Chlamydia trachomatis, it can lead to pelvic inflammatory disease and infertility if left untreated.- Gonorrhea: Caused by the bacterium Neisseria gonorrhoeae, it can cause reproductive tract infections and other complications.- Human papillomavirus (HPV): A viral infection that can lead to genital warts and an increased risk of certain cancers.- HIV/AIDS: Human immunodeficiency virus (HIV) can be transmitted through sexual contact and can progress to acquired immunodeficiency syndrome (AIDS) if left untreated.