Both ceramics and glasses are inorganic, non-metallic solids. They are usually prepared by the action of heat and subsequent cooling. Both materials are typically brittle. However, the definition of ceramic is often restricted to crystalline materials, as opposed to the non-crystalline, i.e., amorphous, glasses. Glasses often optically transparent but ceramics are not.
The earliest ceramics were pottery objects made from clay and hardened in fire. Later ceramics were glazed and fired to create a colored, smooth surface. Ceramics now include domestic, industrial and building products and art objects. New ceramic materials were developed for use in semiconductors and other industries.
The most prevalent type of glass, used for centuries in windows, drinking vessels and bottles, is soda-lime glass. Glass, as a substance, plays an essential role in science and industry. Their chemical, physical, and in particular optical properties make them suitable for applications such as flat glass, container glass, optics and optoelectronics material, laboratory equipment, thermal insulator, reinforcement materials, and glass art.