You have all these Greek letters there. But this is just the sigma right here. That is just the standard deviation of the distribution. We'll play with that a little bit in this chart and see what that means. And well, I mean, you know what the standard deviation is in general, but this is the standard deviation of this distribution, which is a probability density function. And I encourage you to re-watch the video on probability density functions, because it's a little bit of a transition going from the binomial distribution, which is discrete, right? In the binomial distribution, say, oh, what is the probability of getting a 5?