The method used to make champagne requires the wine to be aged inside glass bottles. It starts life in the same way that most wines do. Grapes are harvested from the vineyards and are fermented, meaning that yeast and sugar is added to the grape juices.
When the yeast feeds on sugars in the grapes, carbon dioxide is released into the wine, giving it a slightly fizzy texture. To make a sparkling wine, the containers with the wines are sealed, to keep the gases inside. Different sparkling wines are fermented in different ways, giving them different flavour profiles, and making them stand out from one another.
Its grapes are twice fermented, which is the same as the process used to make prosecco. However, prosecco is fermented in stainless steel vats and champagne is twice fermented in glass bottles. The result is two very different sparkling wines. Champagne retains a dryness and develops a very complex flavour profile. The prosecco develops a much simpler flavour profile and usually stays much sweeter.
Bottling fermenting wine in glass may seem sensible if a winemaker wants to create complex flavours, but it was a very hazardous way to make wine! The build-up of carbon dioxide inside the glass bottles during winter months meant that historically, it was prone to spontaneously explode in cellars! A problem that would eventually be solved by none other than Dom Pérignon himself.