There are several ways you can get infected with the Human Immunodeficiency Virus (HIV):
Through anal intercourse: the behaviour that poses most risk. Even if you use a condom made for anal sex it is not 100% safe, since the condom can easily tear.
Through unprotected intercourse.
Through oral sex. This is less risky than (anal) intercourse, but it is not safe. What you especially should avoid is getting semen or menstruation blood in your mouth.
Through rimming without a dental dam.
By sharing sex toys without covering them with a condom.
By using infected needles and syringes to inject intravenous drugs or steroids.
By being pierced or tattooed by a needle that was used on someone infected with HIV, which was not properly sterilized afterwards. If you get a piercing or tattoo make sure the person uses brand-new needles.
Be careful if you make love to someone who emigrated from a country where many people are infected. Some people are infected by their mother and may be unaware they are HIV positive.