There's a lot of magic inside your vehicle, and very few folks who drive ever take the time to understand the science or systems behind it. And that's fine. You don't have to know all about power steering systems to recognize when your power steering fluid is getting low. All you need to know is that the things that make up your hydraulic power steering system are able to work so smoothly because of a fluid that is in there. It's the fluid that makes your wheel easy to turn and adjust as you need to.