The plane extends indefinitely. In mathematical geometry, a plane is a two-dimensional space without boundaries or restrictions. It is infinitely flat and can extend to infinity. A plane has no beginning and no end. You can select any two points on a plane, and then expand the plane through a straight line between these two points. No matter how many points we take and how many lines we draw on a plane, the plane can always extend indefinitely. Therefore, we can say that the plane is infinitely extended.