A material is a substance or mixture of substances that constitutes an object. Materials can be pure or impure, living or non-living matter. Materials can be classified based on their physical and chemical properties, or on their geological origin or biological function. Materials science is the study of materials and their applications.
Raw materials can be processed in different ways to influence their properties, by purification, shaping or the introduction of other materials. New materials can be produced from raw materials by synthesis.
Materials can be broadly categorized in terms of their use, for example:
Material selection is a process to determine which material should be used for a given application.
In engineering, materials can be categorised according to their microscopic structure::15-17
Materials can be compared and classified by their large-scale physical properties.
Mechanical properties determine how a material responds to applied forces.
Materials may degrade or undergo changes of properties at different temperatures. Thermal properties also include the material's thermal conductivity and heat capacity, relating to the transfer and storage of thermal energy by the material.
Materials can be compared and categorized by any quantitative measure of their behavior under various conditions. Notable additional properties include the optical, electrical, and magnetic behavior of materials.:5-7