STD: Sexually Transmitted Disease
STD refers to any of various diseases transmitted by direct sexual contact that include the classic venereal diseases (such as syphilis, gonorrhea, chancroid, chlamydia, crabs, genital warts, herpes) and other diseases (such as hepatitis A, hepatitis B, giardiasis, and AIDS) that are often or sometimes contracted by other than sexual means.
An essential part of protecting yourself from STDs is to be sure you really know your partner, and don't expect that everyone is entirely truthful about their sexual health. Many people find the embarrassment of discussing STDs so great that they would rather be untruthful than forego sex. Learn more about how to practice safer sex at Planned Parenthood.
You'll also find more information in our What Do You Know About STDs? quiz and AIDS in the ThirdAge article.