Glera is a long-standing synonym of northern Italys Prosecco grape, and the name by which it is now officially known. This green-skinned variety has been grown for hundreds of years in the Veneto and Friuli regions, most famously to produce sparkling Prosecco wines.
The Prosecco-Glera name change happened in 2009, when Prosecco di Conegliano-Valdobbiadene was promoted to full DOCG status (the highest level of Italian wine quality).
In light of this promotion, it was decided that the name Prosecco should be reserved exclusively for wines covered by Italys official Prosecco appellation titles, and should not be used for the grape variety. The European Union ratified this, effectively making it illegal for wine producers anywhere outside northeastern Italy to label their wines as Prosecco.