So for example, if you cared about the probability that the sum of the upward faces after rolling 7 dice, if you cared about the probability that that sum is less than or equal to 30, the old way that you would have to have written it is the probability that the sum of, and you would have to write all of what I just wrote here, is less than or equal to 30. You would have had to write that big thing. And if you wanted to write, and then you would try to figure it out somehow if you had some information. But now we can just write the probability that capital Y is less than or equal to 30. It's a little bit cleaner notation. And if someone else cares about the probability that the sum of the upward face after rolling 7 dice, if they say, hey, what's the probability that that's even, instead of having to write all of that over, they can say, well, what's the probability that Y is even? Now, the one thing that I do want to emphasize is how these are different than traditional variables, traditional variables that you see in your algebra class, like x plus 5 is equal to 6, usually denoted by lowercase variables.