All that bubbles is not Champagne.
Only sparkling wine from "Champagne" — the most northern wine growing region of France — can use the name. Everything else is sparkling wine.
Champagne, however, is the standard against which all bubbly is measured.
Because the region is cool, on the northern fringes of the wine growing climate, the grapes grown there fully ripen in only about half their growing years. Champagne made from those exceptional crops are not blended with any other year and have the vintage in which they were grown printed on the label.
They are expensive. They have to be — yields are small. The process is elaborate and costly and the wine needs aging before release to develop the wonderful complexity of Vintage Champagne. In off years, when the crops are less than ideal, the wine is blended into what have come to be called non-vintage Champagne and therein lay the bargains.
Non Vintage Champagne is more accurately called multi-vintage because of the blending. For simplicity sake let's say that in one year the summer was too hot and the grapes over ripened, the sugar content was too high and the wine a little too sweet. The following year was cool and the wine too acidic. Another year to wet, the wine was thin, next season too dry, you get the point. However, if those wines are blended to balance the sugar and the acid and the richness with the lean, you get a balanced delightful beverage with all the complex characteristics of good single Vintage Champagne at half the price, Voila, Happy Holidays.
Non-Vintage, (NV) Champagne is a great addition to a holiday celebration. Americans tend to think of Champagne as a cocktail wine but Champagne is an excellent accompaniment to food, particularly holiday party food. Look for non-vintage Brut, the driest of this category Champagne to accompany light appetizers and hors d'oeuvres. Enjoy them with stuffed mushrooms, smoked shellfish, oysters, crab dip, ripe cheeses or assorted nuts, especially almonds.