The first thing to know about the word espresso, is that it isn't pronounced "ex-PRESS-oh" but "es-PRESS-oh." There's nothing "express" about espresso coffee drinks. Espresso means literally to press out or extrude--which is what making espresso coffee drinks involves. The word is Italian in origin, deriving from the Latin word exprimere.
Espresso machines were invented in Italy, and in 1905 the patent for the earliest design dedicated to the immediate preparation of served espresso coffee drinks was bought by Desiderio Pavoni, who began manufacturing them in Milan.
Espresso coffee is made by forcing very hot (steaming) water through a densely packed finely ground dark roast powder, which produces a coffee concentrate much stronger and more flavorful than is produced through drip or French press methods.
In Italy, the consumption of espresso drinks at bars encouraged the habit of standing up while drinking it. Espresso drinks proliferated throughout Europe and the Americas in the 20th Century, developing into variations such as capuccino, latte, etc., with the inclusion of milk products and flavorings (sweeteners etc.).
Modern espresso machines are still marketed under the Pavoni name. They come with a steam spout which feeds off the same heating reservoir that provides the steaming water, which is used to steam the milk for the making of lattes or cappuccinos. Everyone has seen the larger models used by restaurants, but the principle is the same, except that the pumping (or pressurization) action can be automated.
Marketer's photo of a modern Pavoni espresso machine (circa 1980's)
Like most people who crave coffee, I eventually discovered the attractions of espresso. When espresso is made, the liquid produces a kind of head or foam on top, known as the crema. This is sort of the créme de la créme, if you will, of the essence of the coffee bean. People have told me that the crema is too bitter, that the real flavor is in the liquid underneath. But this is apocryphal. The crema is in fact the desirable alembic of the brew, and the connoisseur's delight. In France and America, there developed the "au lait" combination, in which steamed whole milk is mixed with freshly brewed espresso. The joining of the crema with the milk foam produces a distinctly refined combination of the natural sugar in milk and the bitter, cocoa-like flavors of the coffee.
Photo of my brass and copper Pavoni espresso machine (acquired about 25 years ago)
Due to the intensity of the espresso flavor, and its high caffeine content, very little espresso can or should be consumed at one time. Indeed, its fragility and evanescence demand that it be consumed within a minute or two of its brewing, since it tends to go "flat" and to cool very rapidly. Whereas regular (or Americano) coffee can be kept warm and relatively fresh for perhaps an hour or more, espresso is only at its best in the first moments after being served, in little demitasse cups small enough for a doll's party.
When in Italy, you will see men in business-suits standing at little open air bars, brief-case in hand, downing an espresso in 15 seconds, then hurrying on to work. You don't see this in America, though there was a little place on Market Street in San Francisco, across from where I worked there in the 1980's, where I used to get a shot or two during my mid-morning break.
We tend to like a double espresso shot after a nice dinner; it's a fitting end to the evening repast. It has less to do with the stimulation than the confirmation of a familiar taste. I suspect that people who smoke may have the same feeling about a good cigarette, or a good cigar after a meal. I've never smoked, so that isn't something I can vouch for.
Ciao, bene, one shot per favore!