The applet illustrates the two basic properties of all vectors: magnitude and direction. It does that using a vector in two dimensions.

The magnitude of the vector can be varied by dragging the vector at its tip. The magnitude is displayed at the bottom of the applet in arbitrary units.

The direction of the vector is specified by the angle between the vector and a horizontal reference line (shown dotted) pointing to the right. The angle is displayed at the bottom of the applet in degrees. The direction can be varied by dragging the vector at its tip.

The vector can be moved without any change in magnitude or direction by clicking near the middle of the vector and dragging the vector.

Note that the number of angles needed to specify the direction of a vector depends on the dimension of the space in which the vector is defined. In three dimensions, two angles are required. In one dimension, no angle is required, but one must specify in which of the two possible directions along a given axis the vector is pointing.