Here's why:

* Magnitude: It describes how fast an object is rotating (measured in radians per second, revolutions per minute, etc.).

* Direction: It also specifies the axis of rotation. This direction is determined by the right-hand rule: If you curl your fingers in the direction of the rotation, your thumb points in the direction of the angular velocity vector.

In contrast, a scalar quantity only has magnitude, not direction. For example, speed is a scalar, while velocity is a vector (it has both speed and direction).

Therefore, angular velocity needs to be represented as a vector to fully capture its properties.