XO cognac is a blend in which the youngest eaux-de-vies are aged in oak barrels for a minimum of 10 years. However, this age designation has changed in recent years. The term was first used in 1870. Until 2016, an eau-de-vie had to be aged for at least six years or more to qualify as an XO. Since April 10, 2016, a new regulation has been in force that raises the minimum age by four years. However, there are still some pre-April 2016 cognacs available for sale.
