The most popular of these is Brut. The sweetness levels are as follows:

Extra Brut: very, very dry, O to .6% residual sugar.
Brut: dry, less than 1.5% residual sugar.
Extra Dry: off-dry, 1.2 to 2% residual sugar.
Sec: lightly sweet, 1.7 to 3.5% residual sugar.
Demi-Sec: quite sweet, 3.3 to 5% residual sugar
Doux: sweet, more than 5% residual sugar.

Most Champagne firms make at least three categories of wine: non-vintage, vintage, and prestige. The vast majority of the Champagne produced each year is designated non-vintage (that is, the blend may contain wines from several different vintages). The wines in a vintage Champagne come only from the year designated on the label.