Scale

Scale modify the size of an object. If the same value k is used for each axis it's called a uniform scale and if different values are used it is called a non-uniform scale.

Scale along cardinal axes

2D =| kx 0  |        
    | 0  ky |
3D =| kx 0  0 |        
    | 0  ky 0 |
    | 0  0  kz|

Scale in a arbitrary direction