A highball is any spirit served with a carbonated beverage over ice. The origin of the term highball is about as difficult to pin down as a champagne bubble. New York bartender Patrick Duffy claimed to have invented it in 1895, and since no one has challenged him, he holds the title. A random poll in most bars would indicate that people have no idea what a highball is—yet it is right in front of them. Scotch and Soda, Gin and Tonic, Coolers, Daisies, and so on are all highballs. A highball is primarily any alcoholic drink meant to refresh.
The highball is served in a highball glass, but that goes without saying. Mixing the drink into an old-fashioned glass makes it a lowball. “Build” the drink in the glass by slowly adding ingredients one at a time. Avoid overstirring freshly opened carbonated beverages. A flat highball is a foul ball.