Pronounced may-tawd shaw-pah-nuaz, it is the traditional way to make Champagne and sparkling wine, and is a sign of quality. It requires the secondary fermentation to be in the bottle, which can last anywhere from several months to 6 years. It is sometimes referred to as méthode traditionelle.
The secondary fermentation is accomplished by adding a mixture of sugar and yeast, called liqueur de triage to the still wine. It is then bottled and capped (with what looks like a beer bottle cap) and laid down to begin the secondary fermentation. The resulting carbon dioxide stays in the bottle, giving the wine those famous bubbles.
It is at the end of this process that the cap is removed and replaced with the familiar cork and wire cage.