Updated January 06, 2015.
Q. What are sexually transmitted diseases or STDs?
A. STDs are diseases that you get by having sex (intercourse, oral or anal) with someone who already has a sexually transmitted disease. STDs are some of the most common infectious diseases (diseases that you get from another person) in the United States today. There are more than 20 kinds of STDs that affect more than 13 million women and men in this country each year.