It is a sparkling, dry white wine made from Glera grapes which are believed to have originally grown naturally in and around the village of Prosecco near Trieste. These grapes are now grown in the hills north of Treviso and between the towns of Conegliano and Valdobbiadene in the Veneto region. Much the same as the 'Champagne' region of France, this area is known as the 'Prosecco' region of Italy and only sparkling wine made from grapes grown in this region can be classed as Prosecco.
Prosecco was originally a slightly sweet sparkling wine, not unlike Asti, but in the 1960's the production methods were changed which resulted in the popular dry Prosecco which is produced today. Unlike Champagne, its main commercial competitor, Prosecco usually is produced using the Charmat method, in which the secondary fermentation takes place in stainless steel tanks. This is a much more cost effective method which makes the wine less expensive to produce. Wines produced by this method can't be aged for very long and Prosecco is best drunk within three years.
There are, as with all wines, different levels of Prosecco with the best and most expensive coming from the Cartizze hill near Valdobbiadene. The grapes for this are grown across 260 acres on the steep slopes of the 300 metre high Cartizze hill and are of the highest quality. The grapes are picked last from these steep slopes, mainly because they are so hard to reach, and the extra ripening time improves their flavour. Bottles from this area are known as the 'Grand Cru' of Prosecco.
Prosecco is light, crisp sparkling white wine with a fresh, fruity flavour and, like all sparkling wines, it should be served chilled. In Italy it is the most popular ingredient of 'aperitivi' and is drunk countrywide for all occasions but elsewhere it is generally drunk in much the same way as champagne. As well as being drunk on its own it is mixed with other things such as Campari and Aperol to make Spritz and can replace Champagne in any cocktails. Most famously it was actually used with peach puree in the famous cocktail Bellini long before Champagne.