Peltier coolers, also known as thermoelectric coolers, are devices that use the Peltier effect to create a temperature difference. They consist of two different types of semiconductor materials that, when an electric current passes through them, transfer heat from one side to the other. This allows one side to become cold while the opposite side heats up. These coolers are commonly used in various applications, such as in portable refrigerators, computer cooling, and laser diodes. They are compact, lightweight, and can be powered by a simple electrical source, making them versatile for both consumer and industrial uses.