A cappuccino is an espresso-based coffee drink that originated in Italy and is prepared with steamed milk foam (microfoam).
Variations of the drink involve the use of cream instead of milk, using non-dairy milk substitutes and flavoring with cinnamon or chocolate powder. It is typically smaller in volume than a caffè latte, with a thicker layer of microfoam.
The name comes from the Capuchin friars, referring to the colour of their habits, and in this context referring to the colour of the beverage when milk is added in small portion to dark, brewed coffee (today mostly espresso). The physical appearance of a modern cappuccino with espresso créma and steamed milk is a result of a long evolution of the drink.
Outside of Italy, cappuccino is a coffee drink that today is typically composed of a single espresso shot and hot milk, with the surface topped with foamed milk. Cappuccinos are most often prepared with an espresso machine. The espresso is poured into the bottom of the cup, followed by a similar amount of hot milk, which is prepared by heating and texturing the milk using the espresso machine steam wand. The top third of the drink consists of milk foam; this foam can be decorated with artistic drawings made with the same milk, called latte art.
In a traditional cappuccino, as served in Europe and artisan coffee houses in the United States, the total of espresso and milk/foam make up between approximately 150 and 180 ml (5 and 6 imp fl oz; 5 and 6 US fl oz). Commercial coffee restaurant chains in the US more often serve the cappuccino as a 360 ml (13 imp fl oz; 12 US fl oz) drink or larger. In Italy, a cappuccino consists of 25 ml (1 imp fl oz; 1 US fl oz) of espresso; the rest of the cup is filled with equal parts of milk and foam. Outside of Italy, the ratios of espresso, milk, and foam typically equal 1/3 each.
Cappuccino is traditionally small (180 ml maximum) with a thick layer of foam, while “latte” traditionally is larger (200–300 ml). Caffè latte is often served in a large glass; cappuccino mostly in a 150–180 ml cup with a handle. Cappuccino traditionally has a layer of textured milk microfoam exceeding 1 cm in thickness; microfoam is frothed/steamed milk in which the bubbles are so small and so numerous that they are not seen, but it makes the milk lighter and thicker. As a result, the microfoam will remain partly on top of the mug when the espresso is poured in correctly as well as mix well with the rest of the cappuccino.
Info and Image from Wikipedia