Sparkling wines made by the same process can't be called Champagne unless they're made in their namesake French region. Chardonnay and pinot noir grapes are the main varieties used to make Champagne, and they're grown all over the world; many regions produce fine sparkling wines that are somewhat less expensive and more widely available than French Champagne. Italian Prosecco and Asti, Spanish Cava and German Sekt are all delicious varieties of sparkling wine. As a side note: the small clusters of grapes sold in the supermarket as "champagne grapes" are just using the cachet of the name: they're actually fresh zante currants.