More often than not, you read about using polarizers to darken the blue sky and make white clouds stand out in a dramatic fashion. Many times too much. But another great feature of the polarizer is cutting down reflections. Under the right angle, you can see through reflective window panes, through water, and many other surfaces. This may also help saturate colors of otherwise reflective surfaces. Instead of glare, you can capture the true color of the surface.

Polarizer Is Not Just for Blue Skies!

As you can see in this picture on the left, taken with a lens without a polarizing filter, the grass in the bottom picked up strong reflections from sun and is throwing the glare at the camera. Sometimes, this may simply result in weaker color in that particular photo section. Other times, it may result in an overall contrast reduction due to glare if the reflections are really strong. 

Now compare to this image on the right. The reflections are gone and the color is back. If this happens to you in a colorful fall foliage scene you can imagine how you could go from low contrast colorless landscape full of glare to a beautifully colorful scene.

Now how about this all green scene? You pick which one you like better.The point here is that not always do you want to remove reflections. For example when photographing animals swimming on a lake, you may actually want to keep the reflections there to separate them from the water that might otherwise swallow them. To the last point you can actually try to use the polarizer again, but for the opposite effect. Rotate it until you see the strongest reflection. If you have the time and a patient subject, try taking several pictures with different rotation of the polarizer and review them later on a larger screen.

Have Fun!