Liquid is one of the the four fundamental states of matter, and is the only state with a definite volume but no fixed shape. a liquid is made up of tiny vibrating particles of matter, such as atoms and molecules, held together by intramolecular bonds. water is, by far, the most common liquid on earth. like a gas, a liquid is able to flow and take the shape of a container. some liquids resist compression, while others can be compressed.