State one use of a Polaroid.

Explanation

**Step-by-Step Solution:**

1. **Definition of Polaroid**: A Polaroid is a special type of material that can polarize light. It consists of thin sheets that selectively absorb certain orientations of light waves.

2. **Understanding Polarization**: Natural light is unpolarized, meaning it contains waves vibrating in all directions. When this light passes through a Polaroid, it only allows the light waves that are parallel to its orientation to pass through, effectively filtering the light.

3. **Identifying Uses of Polaroid**: Polaroids have several practical applications due to their ability to polarize light. One common use is in sunglasses, where they help reduce glare from surfaces like water or roads.

...