What is crema?

In very simple language, the crema is the foam that sits on the top of your espresso shot. At coffeegeek.com, James Hoffmann has given us a very detailed and scientific description of crema, which I highly recommend. For our purposes here, I will just say that you can not have a good espresso without a thick, full crema, just like you can't have a good pint of Guinness without a thick, full head. If your Guinness has no head, then there's something wrong with it--maybe it's been sitting around for a while and went flat, for example. I know I've had a good shot of espresso when, after I've finished my espresso, there's still a coating of crema at the bottom of my cup, and because the shot was so delicious, I find a small spoon, and I scoop up the remaining crema. If you're a cappuccino drinker, you understand the desire to spoon out the frothy milk still sticking to the sides and bottom of your cup, even after the liquid portion of your beverage has been consumed. Sometimes, you try to pour out that sticky froth by turning your cup upside down over your upturned mouth, but you're denied--it just won't pour. You need a spoon. It's the same with good crema--it just won't pour because it's so thick and sticky...and delicious.