A slider is a useful way to offer fine-tuned control over a setting that has minimum and maximum values, or to navigate quickly through a lengthy document. The slider is a track with a little knob that you drag left or right, and you can dress it with icons on either side to represent the minimum and maximum settings—a little speaker and a big speaker in a volume control, for example. In the standard settings, the track is blue to the left of the knob and white to the right, but you can customize those colors to suit your app's palette. (For that matter, you can even customize the knob itself, supplying your own image replacement. As usual, don't stray too far from the standard look, but there's some fun to be had here.)
