As you probably know, light has both wave and particle properties. Polarized light is a product of the wave-like nature of light. Imagine a bunch of light waves coming at you, some are oscillating up and down, others left and right and others in-between. Now imagine you put up a vertical grate (like bars on a window) that was small enough to stop the 'side to side' vibrations, but allowed the vertical ones through (kind of like if you were very skinny and could slip through the vertical bars on your jail cell, but couldn't get through them if you layed horizontally!) The light at the other side of the grate would be "polarized", ie all the light would have the same orientation (in this case, vertical). If you have a pair of polarized sunnies on, then only the vertically oriented light gets through. Imagine light hitting water - it actually works like skimming rocks - the vertical light goes straight into the water but the horizontal light bounces easily back up into your eyes. Therefore if you filter out the horizontal light you can reduce the amount of glare entering your eyes!!! Oh, and if you hold up a vertical polarizer and a horizontal polarizer together then no light will get through... You can try this with two pairs of polarized sunglasses, just put one lense over the other and rotate them... Hope this helps...