Scientists who study (look at and learn about) people who use condoms, see that if teenagers (children 13–19) learn about condoms (and other birth control) they have "less" unsafe sex. Scientists see that learning about these things does not make teenagers start having sex earlier. The teenagers also have "safer" sex. Safer sex means doing things (like wearing condoms) to try not to get pregnant or get sexually transmitted diseases (STDs or STIs) like HIV, gonorrhea, and syphilis. Using a condom works very well for keeping people from getting pregnant or getting STDs if people know how to use a condom the right way. 