Sparkling wines are obtained by primary and secondary alcoholic fermentation of fresh grapes, must and wine and the opening of the bottle releases carbon dioxide produced by fermentation. Their production begins at the time of the Roman Empire, as evidenced by the texts that are still preserved in Italy today. The grape and wine category includes: sparkling wines, quality sparkling wines, quality aromatic sparkling wines and carbonated sparkling wines. The traditional method of production is used to produce natural sparkling wine in a bottle. After the grapes are harvested and pressed, the primary fermentation is followed by the preparation of cuvée, tirage, and yeasts are added to start the secondary fermentation. The secondary fermentation of the wine is carried out in bottles, followed by degorging, addition of liqueur and finally corking. The Charmat method is a method in which secondary fermentation takes place in metal (stainless steel) tanks. The method consists of: preparation of the base, presa di spuma, cooling, filtration, filling and pasteurization. Sparkling wines can also be produced by carbonation which is the addition of carbon dioxide under pressure. Bulk method is used to produce rosé and red sparkling wine. Carbon dioxide exists in the form of dissolved gas and is extracted from it by diffusion or bubble formation. When the bubbles come to the surface, they usually collect in the middle or along the edges of the glass and soon burst. The persistence of a small ring of bubbles (cordon de mousse) along the edges of the glass contributes to the quality of the sparkling wines. The production of sparkling wines is constantly increasing as is consumption. The largest producers are: France, Italy, Germany and Spain and they are also the largest exporters.