A condom is the most common form of protection to reduce the risk of Sexually transmitted diseases (STD's) when when you have sexual intercourse. It is best if you and the person you are going to have sex with talk about protection before you have sex. Both of you are responsible for providing protection from STD's.
Venereal diseases can be passed on when you have sex with someone. Get tested if you think that you may have caught a venereal disease. There is medication that can help available. It is often free.