The material through which a wave travels is called the medium.

Here's a breakdown:

* Waves: Disturbances that transfer energy without transferring matter.

* Medium: The substance (solid, liquid, or gas) that the wave travels through.

Examples:

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

* Water waves: Travel through water.

* Light waves: Can travel through a vacuum (like space) but also through transparent materials like glass.

Note: Some waves, like light and electromagnetic waves, can travel through a vacuum (empty space) without a medium. These are called electromagnetic waves.