Physical properties are characteristics of a substance that can be observed or measured without changing its chemical composition. These properties include attributes such as color, odor, density, melting point, boiling point, and state of matter (solid, liquid, or gas). For example, the density of water is about 1 gram per cubic centimeter, which helps determine whether objects will float or sink. Physical properties are important in identifying and classifying materials. They can help scientists and engineers understand how substances will behave in different conditions. For instance, knowing the melting point of a metal can inform its use in construction or manufacturing processes.