What is the term used to refer to the common initial point from which the arms of an angle originate?

The common initial point from which the arms of an angle originate is known as the vertex. The vertex is the point where two rays meet to form an angle. The other two points on the rays are called the endpoints or the tips of the angle. The two rays are called arms.

For example, in the above figure, point B is the vertex of the angle ABC as ray BA and BC originate from point B.