Sexually transmitted diseases (also known as STDs - or STIs for "sexually transmitted infections") are infectious diseases that spread from person to person through intimate contact. STIs can affect guys and girls of all ages and backgrounds who are having sex - it doesn't matter if they're rich or poor. STIs are more than just an embarrassment. They're a serious health problem. If untreated, some STIs can cause permanent damage, such as infertility (the inability to have a baby) and even death (in the case of HIV/AIDS).
Some of the things that increase a person's chances of getting an STI are:
Sexual activity at a young age. The younger a person starts having sex, the greater his or her chances of becoming infected with an STI.
Lots of sex partners. People who have sexual contact - not just intercourse, but any form of intimate activity - with many different partners are more at risk than those who stay with the same partner.
Unprotected sex. Latex condoms are the only form of birth control that reduce your risk of getting an STI, and must be used every time.
Alcohol and Drug Use. People that are under the influence of drugs are more likely to make impaired judgements and engage in risky behavior.