Not to be stupid...?!
Question: what is an STD???
Answers: what is an STD???
It's a sexually transmitted disease (also called STI for sexually transmitted infection). As the name implies, you can get it if the other person that you are sexually active with has been infected.
STDs usually affect sexual organs, but they can affect other parts of the body. For example, herpes is an STD but if someone shares food with someone who has herpes or kisses them on their mouth, then that person can get herpes even though it wasn't necessarily SEXUALLY transmitted.
And just a clarification to another answer: AIDS is NOT an std. HIV is an std; HIV is the virus that can cause AIDS. Some people can have HIV and not have AIDS.
STDs can be prevented by forms of protections such as condoms, but of course, the most effective protection is abstinence (which means not having sex).
If you should need to know more then talk to a teacher, a guidance counselor, or your parent. Friends might not give you correct info.
Sexually transmitted disease. AIDS, Genital warts, Gonorrhea
Sexually Transmitted Disease
Examples: AIDS, Ghonorria, Syphyllis, Clamdia, Pubic Lice, HPV