Cremant is a sparkling wine produced in either France (Alsace, Bordeaux, Bourgogne, Die, Jura, Limoux, or Loire) or Luxembourg that is similar to champagne in that it is produced via the methode traditionnelle. However, it also follows some other strict production criteria that makes it different.
Grapes for cremant must be harvested by hand within production quotes and the wine must be aged for a minimum of one year. Depending on which of the seven regions a cremant is from, the grapes used in its production can vary wildly.
The other big differences between cremant and champagne is that historically speaking, cremant has approximately half the carbon dioxide of champange making it less bubbly. There you go. Cremant.