Polarized glasses are useful when driving, sailing, skiing, or in any situation where unwanted glare is present. Glare is caused by light reflecting off a surface, such as water, a road, or snow. Such light is polarized. Navigating your way through some situations could be difficult without polarized sunglasses.

Take, for example, light reflecting off the surface of a lake. The light polarized parallel to the water’s surface is reflected with a greater intensity than that polarized perpendicular to the surface. So, sunglasses that pass vertically polarized light will reduce the glare from the water.