Shutters function like an eye lid.  They control how long light enters a camera.  There are two main types of shutters, focal plane and leaf.

Shutter speeds are fractions of a second.  Fast shutter speeds such as 250, 500, or 1000 are good for action shots.

---

Slow Shutter Speeds

Slow shutter speeds such as 1,2, or 4 are good for low light pictures and pictures where water looks soft and like cotton.

---