What are STIs?
Sexually transmitted infections (STIs) are infections people can get from having sex with someone who has one. STIs can be painful and can cause many health problems, even death. STIs can make it hard for a woman to get pregnant or for a man to be able to father children. STIs also can cause problems for babies.
There are many different kinds of STIs. The most common STIs are chlamydia, herpes, genital warts, and trichomoniasis. But gonorrhea, HIV, and syphilis are more common than you might think. About one half of all people will get an STI at some time in their life.