Short definition
A small addition of sugar and wine added to sparkling wine after disgorgement to set the final sweetness level.
After the yeast sediment is expelled from a Champagne bottle, a tiny amount of liquid is added to replace what was lost and to fine-tune sweetness. This mixture of wine and sugar is the dosage. Brut Nature gets zero dosage. Extra Brut gets minimal. Brut allows up to 12 grams per liter. The dosage is the final creative decision before corking — it shapes how you perceive the wine.