Parfait is really a general term used to describe many different types of layered foods served in a dish. In practice, though, most Americans are familiar with ice cream or yogurt parfaits, which are a very specific type of dessert.
The American parfait is very similar to a sundae. It may contain layers of ice cream or cream, and include nuts, syrups, whipped cream, fresh fruit, granola, and any number of other dessert style toppings. It is a popular dessert in fairly upscale restaurants that want to offer something a bit more casual than heavier traditional French desserts. French parfait itself is traditionally made with eggs and cream whipped with a layer of fruit.
The French also make many different items en parfait, and it is not uncommon to find various assorted savory parfaits in France. One finds seafood vegetable, and even fois gras in this form throughout France. The unifying theme tends to be the layering, the somewhat creamy consistency, and the service, which is usually in a tall clear glass.
Parfait has been in America since the late-19th century, although it declined in popularity for many decades. In recent years it has seen a resurgence of interest, and some chefs have begun to experiment wildly with their dishes, bringing them more in line with traditional French parfait in terms of their breadth. The foodie movement, in particular, has embraced the form as a canvas upon which to experiment with creaming innovative ingredients, from broccoli to liver, and making them into dessert-looking entr&eaccent;es or appetizers.
In the last few years, the American parfait has changed in the mainstream, as well. While not as drastic as the shift within the foodie movement, it nevertheless represents an essential change. As people have become more health conscious and begun to move away from wanting to eat large amounts of ice cream, yogurt has become the base of choice for everyday Americans making parfait. This shift is so pervasive that, for many Americans, the term now automatically brings to mind a layered yogurt dessert, although only a few short decades ago that would have been very rare.
The Japanese use the word to refer to dessert as well, although in the Japanese context, parfait is really the same thing as an American sundae. Ice cream is still considered the base, and the additions added are the standard sundae additions, from ground nuts, to hot chocolate syrup, to sprinkles and cherries.