Traditional means a second fermentation in the bottle. Traditional means very long ageing and manual riddling. Traditional means intense, persistent, elegant, tiny bubbles. Traditional. In other words, eternal.
At the end of the 19th century, Federico Martinotti, from Asti, invented the method and the French Eugène Charmat devised the equipment to achieve a second fermentation of the wine in stainless steel pressure tanks. This is how, even today, these bubbles are created.