Most of us refer to the image above as a "three prong" outlet. The technical term is a 110 volt outlet and it is found in most residences.
This is particularly important for your air conditioner purchase. Larger air conditioner units, require a 220 volt outlets. They look like the following:
We've seen instances where a customer ordered an air conditioner, and once they open the box, they realize that they don't have the proper outlet. Usually resulting in frustration, because they have to ask an electrician to wire a 220v outlet and this isn't always possible!