Read the label

A sparkling wine label is a cheat sheet once you know the words. Here's the vocabulary, with the stuff that genuinely changes the taste first.

1. How sweet is it?

On the label	Sugar per litre	What it means in the glass
Brut Nature / Pas Dosé / Dosage Zéro	Under 3 g, no added sugar	Bone dry. Very pure, very crisp. Best with salty or oily food.
Extra Brut	0 to 6 g	Very dry. Fruit and acidity take centre stage.
Brut	Under 12 g	Dry. The most common style, and the safe bet.
Extra Dry	12 to 17 g	Confusingly, a touch sweeter than Brut. Softer and rounder.
Sec	17 to 32 g	Noticeably sweet.
Demi-Sec	32 to 50 g	Sweet. Lovely with fruit desserts.
Doux	Over 50 g	Very sweet, and rare.

Sugar bands from the Comité Champagne. English producers use the same terms.

Vintage / Millésime / a year	Made from one harvest only. Champagne vintage wines need at least three years in the cellar (Comité Champagne).
NV / Non-vintage / Brut Réserve	A blend of years. The house's signature style.
Edition, Cuvée number or Base year	Some producers number their NV releases or give the main year. Domaine Evremond calls its first release "Edition I".

Blanc de Blancs	White grapes only, usually Chardonnay.
Blanc de Noirs	Black grapes only: Pinot Noir and/or Meunier.
Rosé	Pink, usually with a little red wine blended in.

Champagne AOC	Only wine from the Champagne region, made under its rules, can be called Champagne.
Grand Cru / Premier Cru	Champagne made only from grapes grown in villages with those classifications. See Grand Cru, Premier Cru and the English equivalent.
English Protected Designation of Origin (PDO)	100% of the grapes from England, from the classic Pinot and Chardonnay family of grapes, with lab and tasting checks (UK government guidance).
English Regional (PGI)	At least 85% English grapes, and a wider choice of varieties including hybrids.
Sussex PDO	England's first regional quality scheme. Applications go through WineGB.
Traditional method / Méthode traditionnelle / Bottle fermented	The second fermentation happened in the bottle. See How sparkling wine is made.

Look for two small letters near the bottom of a Champagne label (Comité Champagne):

Code	Meaning	What it tells you
NM	Négociant Manipulant	A house that buys at least some grapes. Most big names.
RM	Récoltant Manipulant	A grower making wine from their own grapes. "Grower Champagne".
CM	Coopérative de Manipulation	A cooperative making wine from members' grapes.
RC	Récoltant Coopérateur	A grower selling co-op-made wine under their own label.
ND	Négociant Distributeur	A merchant selling wine it didn't make.
MA	Marque d'Acheteur	A buyer's own brand, such as a supermarket label. Often great value.

English labels don't use these codes. Ask the question in Who actually makes the wine? instead.

Sources