An STD is a disease that is transmitted through sexual intercourse. Traditionally, STDs refer to five types of diseases: syphilis, gonorrhea, soft chancre, lymphogranuloma venereum and inguinal granuloma, caused by Helicobacter syphilis, Dictyococcus gonorrhoeae, Haemophilus ducreyi, Chlamydia trachomatis, and Podococcus granulosus, respectively. Nowadays, STDs generally refer to sexually transmitted diseases, including all diseases that can be transmitted through sexual contact or similar sexual acts. In addition to the five STDs in the traditional sense, they also include non-gonococcal urethritis, genital herpes, condyloma acuminata, trichomoniasis, pubic lice, hepatitis B, and AIDS.