A bimetallic strip is a component commonly used in thermostats. It consists of two strips of metal, with different coefficients of thermal expansion, bonded together. When the strip is heated, the metal with the higher coefficient of thermal expansion expands more than the other, causing the strip to bend. This bending can be used to activate or deactivate a switch, which can in turn control the flow of electricity to a device, such as a heater or air conditioner, thus regulating the temperature.