It's a provably fair algorithm. For more information and to have a glimpse at what it's all about, you can search for it.

You can also see some links directly to a bitcoin casino where there's an explanation about how their provably fair works. Since you are in the progress of understanding how bitcoin casinos work, I think you should encounter that term right now.


Those are different things in general. Try to spend time learning the basics of Bitcoin.

About the casinos, stick on a single site first or those that already established their names. Using several casinos at the same time, especially you are a newbie will just lead you into a confusion of understanding the interface.