This document discusses the three states of matter: solids, liquids, and gases. It defines each state and provides examples. Solids maintain their shape and size, liquids take the shape of their container, and gases have no definite shape and fill their container. The document also notes that some materials can exist in more than one state of matter, and that matter can change states through processes like melting, freezing, and evaporation. It uses water as an example, pointing out that it can exist as ice (solid), liquid water, or water vapor (gas).