Sexually Transmitted Diseases (STDs) are the diseases which are spread by sexual contact from an infected person to a healthy person. They are caused by various microorganisms that live in warm and moist environments of the vagina, urethra, anus and mouth. The four sexually transmitted diseases are:
(i) Gonorrhoea
(ii) Syphilis
(iii) Trichomoniasis
(iv) AIDS (Acquired Immune Deficiency Syndrome). AIDS damages the immune system of human body.