The foundation of most coffee drinks is espresso. It is a dark, strong brew made by forcing hot water under pressure through a finely ground dark roast such as Italian or the even darker French. An espresso is capped by a thin layer of cinnamon-colored crema (foam).
Along with espresso, cappuccino and caffe latte make up the holy coffee trinity. Named for its color's resemblance to the habits of Capuchin monks, cappuccino is made by combining one shot espresso with equal parts steamed milk and milk foam. A latte is essentially a cappuccino without the foam. It is steamed milk and espresso in about a 2:1 ratio. Of course, if you order a double latte, the addition of more espresso throws the ratio out of whack. Still, no foam.
A caffe mocha or mochaccino is one part espresso, one part hot chocolate or chocolate syrup and equal parts steamed milk and milk foam. Remove the foam, top it off with steamed milk, and it's a mocha latte.
Take that poor discarded foam and plop it on top of a shot of espresso and you have a macchiato. If you just dilute a shot of espresso with water or regular brewed coffee, it's a caffe Americano. Add steamed milk to regular brewed coffee, serve it in a big bowl or cup, and you've created cafe au lait.
Then, of course, there's the Starbucks-coined Frappuccino. Think cappuccino meets chocolate malted.