Historically Champagne is a wine region of brands: large domaines both with vineyards in their possession, and contracts with grape growers or 'vignerons' who sell off their fruit. In practice this allows them to blend grapes from different parts of the region into a recognizable house style. Based on the label, any champagne lover will know exactly what is in the bottle, because the champagne will taste the same every year.
Many of the now famous 'grandes marques' have a long history, some of them were founded almost three centuries ago. In those years their cellar masters have experienced great technical changes, like how to handle the pressure in the bottles. By creating fans among French monarchs and Russian tsars, the maisons have made champagne into a globally cherished festive drink.