Grand Cru, Premier Cru… what the what? They are part of the Échelle des Crus which was originally established as a fixed pricing structure, which was formed after the 1910 & 1911 Champagne riots. The Champagne system is a bit different than the system in Burgundy and Bordeaux. While the Échelle des Crussystem was originally conceived as a 1-100 point scale, in practice, the lowest rated villages are rated at 80%. Premier crus villages are rated between 90 and 99 percent while the highest rated villages, with 100% ratings are Grand crus. Note that it is a classification by village, not be vineyard.
The Champagne region has 17 villages that have been designated Grand Cru and 43 Premier Cru villages.
I found a very good website to refer to if you would like to see a very nice glossary of terms. I will be explaining more of them in detail!