This document provides an introduction to the three forms of matter: solids, liquids, and gases. It defines each state of matter and provides examples. Solids maintain a fixed shape and size, liquids take the shape of their container, and gases are invisible and spread out. The document also discusses how water can exist in three states - as a solid (ice) below 0°C, a liquid at room temperature, and a gas (steam) when boiled above 100°C.