10 Things You Didn't Know About Espresso

November 23 is National Espresso Day, and what better way to celebrate than to learn everything there is to know about this drink?

10 Things You Didn't Know About Espresso (Slideshow)

Despite the mechanics of the machine used to make espresso, many coffee lovers will tell you that making the perfect espresso is as much an art as it is a science. 

There are four factors to consider when it comes to making a great shot of traditional, Italian espresso: macinazione (or, the proper grinding of the beans), miscela (the coffee blend), macchina (the machine), and finally mano, literally "hand," meaning the person actually manning the machine. If we're talking true Italian espresso, these four M's are an absolute must. Let's break it down.

Beans for an espresso should be ground to order. It is rare that an Italian barista will serve espresso made from beans that have gone through a pre-grinding process. The grind should be uniform and fine. And, of course, should come be based on good, dark-roasted beans. The blend is up to you.

Almost every Italian household will have a stovetop percolator called a moka that works by passing boiling water pressurized by steam up through a funnel, over the coffee beans, and into a waiting pot. A very different kind of machine is the much more elaborate steam-, piston- or pump-driven appliance found in bars and restaurants.

Finally, the person actually in charge of making the coffee must know what he or she is doing. The right amount of coffee must be added to any machine and the perfect temperatures of every element from water to the inside of the cup must be achieved. Even the barometric pressure can affect the espresso-making process — and while that's outside human control, serious baristas in Italy will adjust their machines according to the barometer.

Who knew there was so much to learn? Here are 10 more things you didn't know about espresso.