Slow Shutter speed
- When you use a Slow shutter speed, you end up exposing your sensor for a significant period of time. The first big effect of it is motion blur. If your shutter speed is long, moving subjects in your photo will appear blurred along the direction of motion. This effect is used quite often in advertisements of cars and motorbikes, where a sense of speed and motion is communicated to the viewer by intentionally blurring the moving wheels.
Slow shutter speeds are also used to photograph the Milky Way or other objects at night, or in dim environments with a tripod. Landscape photographers may intentionally use long shutter speeds to create a sense of motion on rivers and waterfalls, while keeping everything else completely sharp.
Ref - https://photographylife.com/what-is-shutter-speed-in-photography