Champagne's bubbles are not added. They are grown — inside the bottle, over months or years, by yeast eating sugar in a sealed glass container and producing carbon dioxide that has nowhere to go. When the cork is removed, the pressure (approximately 6 bar — three times the pressure of a car tyre) forces the dissolved CO₂ out of solution as millions of tiny bubbles.
The reason this process produces something exceptional in Champagne specifically — and not just fizzy wine — is the terroir. The Champagne region sits at approximately 49°N latitude on a thick bed of Cretaceous chalk. The chalk's high porosity stores moisture while draining freely; its calcium carbonate content creates a distinctive mineral quality in the wines. The cool climate (mean temperature ~10°C annually, regular spring frosts) means grapes ripen slowly and incompletely — producing a base wine of very high natural acidity, relatively low alcohol (7–9%), and delicate fruit character. This thin, tart base wine is, frankly, almost undrinkable on its own. But it is ideal for the méthode champenoise: the secondary fermentation adds body and complexity, the lees ageing adds depth, and the dosage (a small addition of sugar and wine before final corking) adjusts the sweetness to the final style.
Vintage Champagne — labelled with a specific year — is made only in years when the harvest is considered sufficiently outstanding to stand alone without the blending support of reserve wines. Most houses declare a vintage only 2–4 times per decade. Vintage Champagne must be aged on the lees for minimum 36 months (vs 15 months for NV).