White noise is one of the fundamental building blocks of sound synthesis. It sounds a bit like a waterfall. It's essentially a purely random sound, with each frequency being roughly equally loud to the others.

It can be useful to filter white noise into other metaphorical colours that get louder or quieter with every octave:

Colour Difference per octave
Red -6 dB
Pink -3 dB
White 0 dB
Blue +3 dB
Violet +6 dB

Practical uses

You can bandpass filter the middle frequencies of white noise to make the actual snare part of a snare drum. In a separate part of the patch, the drum part of the snare drum is the same as the kick drum, only tuned up about an octave. In the studio with multitrack recording, not live, you can wire these up as two separate patches recorded on two separate channels, to reuse modules between the two.

You can hipass filter the high frequencies of white, blue, or violet noise to make a hi-hat. While ring modulation sounds more metallic, noise gives you a nice hissing sound.

If you run noise through a particularly resonant bandpass filter that's tuned to melodic pitches, you can play a tune on it. You can hear an example of this on Global Communication's 9:25, at the 2:28 mark. I played around with this on Martian Wind.