1. Space and its Dimensions
What is meant by ‘3D’?
The abbreviation ‘3D’ stands for ‘threedimensional’. This can be very simply illustrated by the movements of the red ball in the following images.
 When a ball is only able move to the right and the left (in one line), this ball is located in a onedimensional space.
 If the ball has the possibility to move not only to the left and to the right, but also backwards and forwards, this ball is located in a twodimensional space.

A threedimensional space is, for example, a closed box where the ball has the
possibility to move:
 to the left and to the right
 backwards and forwards
 upwards and downwards
The three dimensions are:
 to the left and to the right (width)
 backwards and forwards (depth)
 upwards and downwards (height)
These three dimensions make it possible to observe this 3D world out of different points of view: the front, the back, the sides, the bottom and the top.