Question

give some examples of parallel beam of light

Answer 1

Instead of parallel rays, consider the light as a wave front. It leaves the source in a spherical wavefront. At a certain distance the sphere is so large and the curvature of the wavefront becomes so small that it can be considered locally flat, and behaves optically as though it were flat. At that point, the flat wave front is equivalent to parallel rays (which are perpendicular to the front).

Answer 2

spotlights, searchlights