A heat pump is a device that moves, or "pumps", heat from one location to another, usually using electricity to power the system. You probably already know about several heat pumps that go by different names: for example, your refrigerator and freezer are heat pumps that pump heat from inside the box and send the heat into your kitchen. By removing heat from the box, the inside is made cold. Another example: if you have an "air conditioner" that provides space cooling, that's a heat pump as well! That type of device moves heat from indoors and sends the heat outdoors in order to make your living space cooler.
Generally, when we talk about heat pumps in the U.S., we're talking about systems that are designed to provide both heating and cooling, depending on the season. They move heat indoors in the winter, and they remove heat from the indoors in the summer (to make the indoors cooler).
How can a heat pump get heat from the cold outside air? That's a great question. Here's the simple answer...Have you ever used a magnifying glass to concentrate sunlight into intense heat? A heat pump in heating mode does something similar - it concentrates tiny bits of heat from the outdoor air into a small pipe. Then, it delivers that heat indoors for comfort. The more complex answer