Hard seltzer, spiked seltzer or hard sparkling water is a type of highball drink containing carbonated water, alcohol, and often fruit flavoring.
In the US the alcohol is usually made by fermenting cane sugar; sometimes malted barley is used.
Hard seltzer products outside of the US have been found to use either neutral spirit, or fermentation of fruit. The alcohol by volume is around 5% and the calorie-content is relatively low.
5th generation brewer Nick Shields invented the beverage style with Spiked Seltzer, in Westport, Connecticut, and brewed the first commercial batches in November, 2013. The category saw a spike in popularity around 2018–2019 in the U.S.