### The standard unit vectors

A unit vector is a vector whose magnitude (or length) is one. The *standard unit vectors* are the special unit vectors that are parallel to the coordinate axes, pointing toward positive values of the coordinate.

#### Two dimensions

*The standard unit vectors in two dimensions.* The standard unit vectors in two dimensions, $\vc{i}$ (green) and $\vc{j}$ (blue), are length one vectors that point parallel to the $x$-axis and $y$-axis, respectively. Moving them with the mouse doesn't change the vectors, as they always point toward the positive direction of their respective axis.

#### Three dimensions

#### Applet loading

*The standard unit vectors in three dimensions.* The standard unit vectors in three dimensions, $\vc{i}$ (green), $\vc{j}$ (blue), and $\vc{k}$ (red) are length one vectors that point parallel to the $x$-axis, $y$-axis, and $z$-axis respectively. Moving them with the mouse doesn't change the vectors, as they always point toward the positive direction of their respective axis.