So that line, you could view this as a regression line. We could view this as y equals mx plus b, where we would have to figure out the slope and the y-intercept, and we could figure it out based on what I just drew, or we could even think of this as weight. Weight is equal to our slope times height, times height plus whatever our y-intercept is, or you could think of it, if you think of the vertical axis as the weight axis, you could think of it as your weight intercept. But either way, this is the model that I'm just, through eyeballing, this is my regression line, something that I'm trying to fit to these points. But clearly it can't go through, one line won't be able to go through all of these points. There is going to be, for each point, some difference, or not for all of them, but for many of them, some difference between the actual and what would have been predicted by the line. And that idea, the difference between the actual four-point and what would have been predicted given, say, the height, that is called a residual.