Well, let's say, and we're going to introduce a little bit of calculus now. Let's say that we have a particle's velocity function. And so let's say our velocity as a function of time is equal to five minus t. Now this is a one-dimensional velocity function. Let's say it's just telling us our velocity in the horizontal direction. And oftentimes when something's one dimension, people forget, well, that too can be a vector quantity. In fact, this velocity is a vector quantity because you could think of it, if it's positive, it's moving to the right, and if it's negative, it's moving to the left. So it has a direction.