And that's the normal distribution, or the Gaussian distribution, or the bell curve. And just to kind of give you a preview of what it is, and my preview will actually make it seem pretty strange, but as we go through this video, hopefully you'll get a little bit more intuition of what it's all about. But the Gaussian distribution, or the normal distribution, they're just two words for the same thing. It was actually Gauss who came up with it. I think he was studying astronomical phenomenon when he did. But it's a probability density function, just like we studied the Poisson distribution. It's just like that.