Simple shapes
The perimeter of a shape is the distance around its boundary. This is a length, and is said to have \({1}\) dimension (1D).
Example
An ant walks all the way around the edge of a rectangle, measuring \(3~cm\) by \(4~cm\).
What distance will it have travelled?
Perimeter \(= 4 + 3 + 4 + 3 = 14~cm\)