* Solid: Has a definite shape and volume. The particles are tightly packed and vibrate in place.

* Liquid: Has a definite volume but takes the shape of its container. The particles are close together but can move around.

* Gas: Has no definite shape or volume and expands to fill its container. The particles are far apart and move freely.

There is also a fourth state of matter called plasma, which is a superheated gas where electrons are stripped from atoms, making it electrically conductive.