Sexually transmitted diseases -STDs- (previously known as venereal diseases), are infections that are spread from one person to another, usually during vaginal, anal or oral sex. They are very common, and many people with STDs have no symptoms. That's why it's important to get tested regardless of whether you have symptoms of STDs or not. Without treatment, STDs can cause serious health problems. The good news is that getting tested is not complicated, and most of these infections are easy to treat.