These two designations are defined by the amount of sugar cane in the wine.

There are two sub-categories of Champagne: “brut” and “demi-sec”. These two designations are defined by the amount of sugar cane in the wine. Different types of Champagne range between demi-sec and brut, depending on how much sugar cane is in them.
A demi-sec Champagne will contain between 33 and 50 grams of sugar, whilst a dry (“sec”) champagne will contain between 17 and 35 grams. An extra-dry Champagne will contain between 12 and 20 grams of sugar, and a brut Champagne will have less than 15 grams. The Champagne with the least amount of sugar is known as “extra-brut”, and contains no more than 6 grams of sugar – sometimes, it has no sugar added to it at all.

How should you drink your demi-sec or brut Champagne?

You need to be aware that brut and demi-sec Champagnes each have their own distinct gustatory traits, and during a meal, they should therefore be consumed at the appropriate time. It follows that demi-sec, being the most sugary variety, is normally drank with dessert, and inversely, the low-sugar brut Champagne can be enjoyed as an aperitif and throughout the meal, as it has a lively and refreshing taste. That said, extra-brut Champagne is almost always solely reserved for consumption as an aperitif, as it contains barely any sugar at all.

Lastly, when trying to choose a quality Champagne, pay attention to its colour: a rich colour is a sign of a mature Champagne. You can also garner priceless information about the origin of the Champagne you wish to buy by taking a look at its label (name of the grower, brand, etc.).