Read the passage below and answer the question.

If we look clearly at the shadow cast by an opaque object, close to the region of geometrical shadow, there are alternate dark and bright regions. This happens due to a particular phenomenon. It is a general characteristic exhibited by all types of waves, be it sound waves, light waves, water waves or matter waves.

What is this phenomenon in question?

Diffraction

Deviation of light into the geometrical shadow occurs by the phenomenon of diffraction.