Earlier Indian and Greek philosophers and scientists attempted to classify the matter in the form of five elements - Air, Earth, Fire, Sky and Water. This classification was more of philosophical nature. In modern science, however, there are two main ways of classifying the matter :

i) Based on physical states: All matter, at least in principle, can exist in three states, solid, liquid and gas.

ii) Based on composition and properties: The classification of matter includes elements,compounds and mixtures.