A thermostat is a device that can sense the temperature and automatically control the heating or cooling system to achieve and maintain the desired temperature.

This can be very useful because it can make your heating and cooling system much more efficient. If you don't have a thermostat, the heating or cooling will run constantly, which can lead to higher energy bills. However, with a thermostat, the heating or cooling only works when it is needed, saving energy and money.

In addition, the thermostat allows for more convenient temperature control. The thermostat is usually programmable, so you can set the temperature in your home to be the desired temperature only when you are at home and lower when no one is home. This can reduce heating and cooling costs and make life more comfortable at the same time.