Math of GR
Part 4

Next, mark each black mark on each of the three axes with a number, equal to the number of inches it is away from the origin. So now you have three rods with black marks on them, looking like thin rulers. And on them are three orange marks, signifying WHERE THE BALL IS. Right? I hope you can see that.

For instance, say that the orange mark on the Z axis is at mark 12. The orange mark on the X axis is on the 10, and the orange mark on the Y axis is on the 3. We can now "quantify" the location of the ball by saying that it is at (10, 3, 12), where we always list first its X position, then its Y position, then its Z position.