Seltzer

Carbonated water is water containing dissolved carbon dioxide gas, either artificially injected under pressure or occurring due to natural geological processes. Carbonation causes small bubbles to form, giving the water an effervescent quality. Common forms include sparkling natural mineral water, club soda, and commercially produced sparkling water. Club soda and sparkling mineral water and some other sparkling waters contain added or dissolved minerals such as potassium bicarbonate, sodium bicarbonate, sodium citrate, or potassium sulfate. These occur naturally in some mineral waters but are also commonly added artificially to manufactured waters to mimic a natural flavor profile and offset the acidity of introducing carbon dioxide gas giving one a fizzy sensation. Various carbonated waters are sold in bottles and cans, with some also produced on demand by commercial carbonation systems in bars and restaurants, or made at home using a carbon dioxide cartridge.

Source: Wikipedia