Light that brings magic and beauty to everything it touches
Just after sunrise and just before sunset is the time of day that brings light that photographers love so much that they often call it "magic hour." Golden hour (which really can be a matter of a few minutes, not a full hour) is the time of day where the sun is low on the horizon and the quality of light is softer, more red-ish and gold, and creates opportunities for incredible exposures with softer highlights and shadows -- and indeed as in this photo of a bobcat on a trail, more opportunity to capture stunning silhouettes. Some photographers go so far as to consider it the only time of day worth shooting.
Wikipedia describes the science: "When the sun is near the horizon, sunlight travels through a greater depth of atmosphere, reducing the intensity of the direct light, so that more of the illumination comes from indirect light from the sky, reducing the lighting ratio. More blue light is scattered, so if the sun is present, its light appears more reddish. In addition, the sun's small angle with the horizon produces longer shadows."
But what we really only need to know is that this is the time of day where light is at its most stunning, and many photographers aim to shoot at this time of day because of the soft beauty the light lends to everything it touches. There is an element of dreaminess, of fairytale, of emotion that can be captured more easily than at most other times of day.
If you're curious about how your photography changes depending on the light, try this experiment: grab your camera and head out to start shooting from the early afternoon through to dark. It is easiest to pick a single subject like a certain landscape, but it also works if you just wander around on a hiking trail or even through city streets. At the end of the evening, look through what you've captured and notice how the light shifts the mood, colors and quality of your photos. If you've never tried this, you might be simply amazed at the difference -- and the impact of golden hour.