Unit Vector

A vector has magnitude (how long it is) and direction:

vector magnitude and direction

A Unit Vector has a magnitude of 1:

unit vector

The symbol is usually a lowercase
letter with a "hat", such as:

(Pronounced "a-hat")

Scaling

A vector can be "scaled" off the unit vector. Here vector a is shown to be 2.5 times a unit vector. Notice they still point in the same direction:

vector unit scale 1 to 2.5

Unit vectors can be used in 2 dimensions:

vector a = 2x + 1.3y

Here we show that the vector a is made up of 2 "x" unit vectors and 1.3 "y" unit vectors.

Likewise we can use unit vectors in three (or more!) dimensions:

vector unit 3d