What do the terms Energuide and Energy Star mean? How can they be used when purchasing appliances?

What do the terms "Energyguide" and "Energy Star" mean? How can they be used when purchasing appliances or electronics?|||You can find exact definitions on line with a simple search. Basically they tell you how much power in a year the appliance will use relative to similar appliances so that you can make a buying decision on buying a more efficient appliance that may cost more due to better insulation or hold less because of thicker walls.