Here's why:

* Mechanical waves require a medium (like air, water, or a solid) to propagate. The particles in the medium vibrate and transfer energy, creating the wave.

* Examples of mechanical waves:

* Sound waves

* Seismic waves (earthquakes)

* Waves on a string

* Water waves

Electromagnetic waves, on the other hand, do not require a medium and can travel through a vacuum (like space).