Espresso is coffee served from a very fine powder that is packed into portafilter and put into an espresso machine.
Water heated to 190-197 degrees Fahrenheit is pressed below 8-10 atmospheric pressure through a fine coffee portafilter to produce 1-2 ounces of espresso.
A good way to tell if your espresso is high quality or can not be seen from the color and consistency of the cream. If you add sugar, pour over cream for 15-30 seconds.