Here's why:

* Transparent materials allow most of the light that hits them to pass through, with little to no scattering. This allows us to see objects clearly through them. Examples include glass, water, and air.

* Translucent materials allow some light to pass through, but scatter it so objects can't be seen clearly. Think of frosted glass or thin paper.

* Opaque materials block all light from passing through. You can't see through them at all, like wood or metal.