Your Guide to Sexually Transmitted Diseases
Sexually transmitted diseases, commonly called STDs, are diseases that are spread by having sex with someone who has an STD. You can get a sexually transmitted disease from sexual activity that involves the mouth, anus, vagina, or penis.
According to the American Social Health Organization, one out of four teens in the United States becomes infected with an STD each year. By the age of 25, half of all sexually active young adults will get an STD.