You can also view previously answered questions in the HSW Question Archive . It's frozen water, and water isn't white, it's clear. Snow wouldn't be snow if it wasn't white. But if you think about it, it seems weird that snow is white at all, since it's just a bunch of ice crystals stuck together. To understand where the whiteness comes from, we need to back up and look at why different things have different colors in the first place.
Visible light is made up of many different frequencies of light.
Our eyes detect different frequencies as different colors. Basically, the electrons of the particle will vibrate a certain amount in response to energy, depending on the frequency of the energy. In the case of light energy, the molecules and atoms absorb a certain amount of light energy depending on the frequency of the light, and then emit this absorbed energy as heat. This means that objects absorb certain frequencies of light more than others. A couple of different things can happen to the light frequencies that are not absorbed.