So what's the meaning of this definite integral? So the velocity, velocity is a vector, it has direction. And you can see, when you look up here, that sometimes the velocity is positive and sometimes it is negative. And a reasonable interpretation of that is, well, this is when she's walking in one direction and then that's whatever direction we assume is the positive direction, and this is when she's walking the other way. And so she has a positive velocity here and then she has a negative velocity, she has some speed in the other direction, and then she has a positive velocity again. So if you were to take the absolute value of this, if you just cared about the magnitude of the velocity, well, we're talking about speed. But we're not just talking about the absolute value of velocity, we're integrating the absolute value of velocity over time, from time equals zero to time equals 40.