You've probably seen or used a thermostat a thousand times. This device controls the heating and air-conditioning systems in your house -- the two pieces of equipment that use the most energy. In these days of rising energy prices, you might be interested to see how your thermostat works. It is surprisingly simple, and contains some pretty neat technology.

In this edition of HowStuffWorks we'll take apart a household thermostat and learn how it works. We'll also learn a little about digital thermostats. Let's start by taking a look at the parts.