A real object has three dimensions. However, when drawing an object on paper, it is only possible to show it in two dimensions. Use projection techniques to give the illusion of three-dimensionality.
A projection is the name for certain methods used to draw a solid or an object.
A projection is a transformation that consists of drawing points of a two-dimensional figure that correspond with a reference object.
In contrast, a perspective is a two-dimensional representation of a three-dimensional object that uses parallel or converging (vanishing) lines.
There are several types of projections. Each of them are constructed in different ways.
To see the differences between the three types of projections, take a look at an an example of each one from the following rectangular prism.
As seen in the initial object, the hidden faces are represented with dotted lines. However, it is possible for the drawing to become too dense, so these lines are sometimes omitted.