There are some main acts that can result in fluid and site coming together, resulting in a potential infection.
The main ones are having unprotected sex (we’ll get to protection tools later) with someone who has HIV and sharing needles with someone living with HIV when you inject drugs.
The important thing to know is that while each time you have unprotected sex with someone who is HIV positive the likelihood you’ll become infected is pretty low (an estimated 0.08 percent if an infected penis goes into your vagina, an estimated 0.04 percent if your penis goes into an infected vagina, and an estimated 1.4 percent if an infected penis goes into your butt), those numbers are true every time you do that act.
So the risk can pile up if you’re having sex with an HIV positive person multiple times.
Since that’s not how most adults operate, the good news is that there are an increasing number of ways you can protect yourself against becoming infected with HIV, while still being able to connect sexually with your HIV positive partner.