Coordinates

By pressing F3 you can view your current location in the minecraft world represented by the X, Y, Z, and F coordinates at the top left of the screen.

Your X-Axis is how far north (or south in the case of a negative number) of zero you are.

Your Y-Axis represents your height. Y 64 is sea level for example.

Your Z-Axis is how far east (or west in the case of a negative number) of zero you are.

F is a new coordinate and represent which direction you are currently facing. F0 is West F1 is North F2 is East F3 is South. This would really only be useful in the event that you are unable to look up at the clouds to tell your direction, since clouds travel North.