A cappuccino is generally defined as 1/3 espresso, 1/3 steamed milk and 1/3 frothed milk.

In Italy it is consumed mainly early in the day for breakfast, although it is not uncommon at all today to see Italians drinking it (alone) throughout the day; except for breakfast time, where it's consumed with cookies, biscuits, and croissants.

Italians never drink it with meals; in some other countries it may be consumed throughout the day or after dinner.

Besides a quality shot of espresso, the most important element in preparing a cappuccino is the texture and temperature of the milk. When a well-trained barista steams the milk for a cappuccino, he or she should create microfoam by introducing very tiny bubbles of air into the milk. This gives the milk an extremely velvety texture and sweet taste.

A cappuccino is ideally prepared in a ceramic coffee cup, which has far better heat retention characteristics than glass or paper.

In some places, skilled baristas create latte art when pouring properly steamed milk into the espresso, making designs such as apples, hearts, leaves and rosettes.

Named for after the hooded robes worn by the Capuchin monks, cappuccino was a taste largely confined to Europe and a few of the more cosmopolitan cities of North America until the mid-1990s when cappuccino was made much more widely available to North Americans, as part of the new upscale coffee bar chains with a consciously "European" air (notably Starbucks).

By the first years of the 21st century a modified version of cappuccino was being served by McDonald's. At America's most popular coffee chain, Starbucks, one must order the off-the-menu "Short Cappuccino" to get a drink that is approximately 1/3 espresso and 2/3 microfoam.

The widespread acceptance in the U.S. of what was once regarded as a taste of coastal urbanites and older Italian-Americans has led to many establishments, such as convenience stores offering what they represent as cappuccino to their patrons.

However, that product is usually an ersatz cappuccino, produced by machines similar to those that mix cocoa drinks where all the buyer need do is touch a button and position the cup properly. The drink that comes out is usually produced either from a preproduced mix or double-brewed coffee and bears little relation to the real thing.

Similar products result from home use of store-bought mixes usually advertised, more accurately, as producing "frothed coffee."

Source: Wikipedia

The Americanization of Cappuccino