SD 600 Shutter Speed

I am trying to figure out everything i can about my SD 600 camera.
I got it for Christmas and LOVE it.
When I was reading the manual it talked about shutter speed and how it will automatically adjust to light BUT here is what I do not understand. To avoid blurrness it says use a higher shutter speed. It does the automatically in the dark. What i don't understand is WHY would one use a slower shutter speed? Why are there more than one speed... because don't we all aim not to have fuzzy pictures?

There are two kinds of "fuzzy" pictures from slow shutter speeds. The first is from you, the photographer, shaking the camera. This is almost always undesirable (panning the camera incorporates some of this; there is/was also a fad around whose devotees would throw the camera up in the air while it was taking the picture just for the effect they'd get), and can be compensated for by setting the camera on a tripod or other solid support. The other cause is when the subject is moving but the camera isn't.

Sometimes you want to use a slow shutter speed to capture the blur of the moving object. Think of photos you may have seen showing headlight streaks on a road, or shots where someone's panned on a car, so the car's sharp against a blurred background. Or beach or stream scenes with a velvety-smooth water surface. So sometimes "fuzzy" may be good.

Sometimes you need a slow shutter speed because there just isn't enough light, even at maximum aperture, to get a decent exposure at a faster speed.

Most basic photography books will explain some of hte considerations in selecting/seeking a given shutter speed. One that's especially popular around here is Bryan Peterson's Understanding Exposure. You might want to hunt down a copyu. Or anything by John Hedgecoe.