Here's why:

* Electromagnetic Radiation: This is a broad category encompassing all types of waves that travel at the speed of light. These waves consist of oscillating electric and magnetic fields.

* Gamma Rays: These are the highest energy and shortest wavelength type of electromagnetic radiation. They are produced by nuclear processes like radioactive decay and nuclear explosions.

So, while you can think of gamma rays as waves, they are specifically a type of electromagnetic wave, just like visible light, radio waves, and X-rays.