Solidification, also known as freezing, is a phase change of matter that results in production of a solid. Generally, this occurs when the temperature of a liquid is lowered below its freezing point. Although the freezing point and melting point of most materials are the same temperature, this is not the case for all substances, so freezing point and melting point are not necessarily interchangeable terms. For example, agar (a chemical used in food and the laboratory) melts at 85°C (185°F) yet solidifies from 31°C to 40°C (89.6°F to 104°F).