­Wouldn't it be nice to know how these indispensable machines work their magic?

­ Air conditioners come in various sizes, cooling capacities and prices. One type that we see all the time is the window air conditioner, an easy and economical way to cool a small area:

People who live in suburban areas usually have one of these in their backyard:

If you live in an apartment complex, this is probably a familiar sight:

Most businesses and office buildings have condensing units on their roofs, and as you fly into any airport you notice that warehouses and malls may have 10 or 20 condensing units hidden on their roofs:

And then if you go around back at many hospitals, universities and office complexes, you find large cooling towers that are connected to the air conditioning system:

Even though each of these machines has a pretty distinct look, they all work on the same principles. In this article, we will examine air conditioners -- from small to huge -- so you know more about what you're seeing.