Having unprotected sex and multiple sex partners places you at higher risk for STDs. Many STDs have no symptoms when you are first infected, so you may have an infection without knowing it. If you are sexually active, be sure to have regular check-ups that include STD screenings so if you have an infection it can be detected and treated (if possible) at its earliest stages.

More than half of teens (51 percent) who are sexually active say they used a condom the last time they had sex, according to a 2001 CDC survey. However, only about 25 percent of teenagers say they consistently use a condom.

When used correctly, male latex) condoms and female condoms used during sexual intercourse can help reduce your risk of getting many STDs, including HIV (the virus that causes AIDS), but male and female latex condoms don't prevent all STDs transmitted by skin-to-skin contact.

Other contraceptives, like birth control pills, and spermacides that contain a chemical called nonoxynol-9, will help prevent pregnancy, but don't protect you from STDs. In fact, spermacides containing nonoxynol-9 can increase vaginal irritation, which may actually increase your chances of getting an STD from an infected partner, according to the U.S. Food and Drug Administration.

Asking questions about sexual topics may feel awkward and embarrassing. It can be an uncomfortable thing to talk about. But if you are sexually active or considering having sex, not knowing about STDs is dangerous. That lack of knowledge can harm you, or even kill you. Get the facts from someone who knows, whether it's a parent, brother or sister, health care professional or teacher.