Physical materials are substances that have a definite shape and volume. They can be classified into three main categories: solids, liquids, and gases. Solids, like wood and metal, maintain their shape, while liquids, such as water and oil, take the shape of their containers. Gases, like oxygen and carbon dioxide, have no fixed shape or volume and expand to fill the available space. These materials are essential in various applications, from construction to manufacturing. Understanding their properties, such as density, melting point, and conductivity, helps in selecting the right material for specific uses, ensuring efficiency and safety in different industries.