The type of wave that does not move in a medium is an electromagnetic wave.

Here's why:

* Mechanical waves require a medium to travel. This means they need particles (like air molecules, water molecules, or the molecules of a solid) to vibrate and transmit the wave energy. Examples include sound waves and water waves.

* Electromagnetic waves are made up of oscillating electric and magnetic fields. They can travel through a vacuum (like space) because they don't need a medium to propagate. Examples include light waves, radio waves, microwaves, and X-rays.

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