If photographing sports, action, wildlife, or whales, chances are you want to freeze the moment so the viewer can take it in. Situations like this call for a fast shutter speed, like 500th-1000th of a second.
When photographing landscapes that have an ocean or stream as part of the composition some photographers may want to freeze the water splashing on the rocks, while others may want to drag the shutter or slow it down. The longer the shutter is open, the more movement of water is recorded and as a result there is more emotion.
