A thermostat is a device that is used to control the temperature of a room or space. It works by sensing the temperature of the environment and then adjusting the heating or cooling system accordingly. The most common type of thermostat is the mechanical thermostat, which is usually a dial or knob that can be adjusted to set the desired temperature. More advanced thermostats are digital and can be programmed to maintain a certain temperature range or to turn on and off at certain times. The main purpose of a thermostat is to provide comfort and energy efficiency. By setting the thermostat to the desired temperature, the heating or cooling system will only run when necessary, saving energy and money. In addition, the thermostat can be used to ensure that the temperature of a room or space is comfortable for the occupants.