When you are asked to classify matter, you probably automatically think of the phases or states of matter: solid, liquid, gas, and plasma. However, scientists also classify matter according to the substances that make up the matter, or its composition. When classifying matter according to composition, all matter can be classified as either a pure substance or a mixture.
The diagram below shows the classification of matter according to composition. Click on each term to see a brief explanation. You will learn more about each of these terms in different sections of this resource.