Reflections are often unwanted, and glare will wash out an image. Polarizing filters counter the reflective measures and will deepen blues and add contrast to skies, reduce or remove reflections from water and windows, and increase contrast and saturation.
A video is made up from 25 single photos per second, that, when placed back-to-back, trick our mind into seeing motion. But what would happen if we only took one photo every minute, and then played them back at 25 frames per second? The result is a magnificent hyper-realistic compression of time.
When you focus your camera, the area around the focal distance will also be in focus. But this can fall off to blur quickly or slowly. The acceptable amount of in-focus area around what's you are focusing on is called depth of field.