Waves that require a material medium to propagate are called mechanical waves.

Here's why:

* Mechanical waves are disturbances that travel through a medium by transferring energy from one particle to the next. The particles themselves oscillate but don't travel long distances. The medium provides the necessary forces for the wave to move forward.

Examples of mechanical waves:

* Sound waves: Travel through air, water, or solids.

* Water waves: Travel through water.

* Seismic waves: Travel through the Earth's crust.

* Waves on a string: Travel along a stretched string.

Contrast this with electromagnetic waves:

* Electromagnetic waves do not need a medium to travel. They can propagate through a vacuum (like space). They are disturbances in electric and magnetic fields that travel at the speed of light.

Examples of electromagnetic waves:

* Light waves

* Radio waves

* Microwaves

* X-rays

* Gamma rays