mechanical waves are waves that require a medium. This
means that they have to have some sort of matter to travel through.
These waves travel when molecules in the medium collide with each other
passing on energy. One example of a mechanical wave is sound. Sound can
travel through air, water, or solids, but it can't travel through a
vacuum. It needs the medium to help it travel. Other examples include
water waves, seismic waves, and waves traveling through a spring.
Electromagnetic waves are waves that can travel through a
vacuum (empty space). They don't need a medium or matter. They travel
through electrical and magnetic fields that are generated by charged
particles. Examples of electromagnetic waves include light, microwaves,
radio waves, and X-rays.