* Solids: Have a definite shape and volume (e.g., rocks, ice, wood)
* Liquids: Have a definite volume but take the shape of their container (e.g., water, oil, mercury)
* Gases: Have no definite shape or volume and take the shape and volume of their container (e.g., air, oxygen, carbon dioxide)
* Plasma: A state of matter where atoms are stripped of their electrons, forming an electrically charged gas (e.g., the sun, lightning)
In essence, everything you can see, touch, or feel is made up of matter.
