Soda water is a generic name for naturally or artificially carbonated water that is slightly alkaline and meant to mimic naturally occurring mineral water. Carbon dioxide dissolves into water to produce carbonic acid, which neutralizes some of the alkaline additive.
While alkaline sparkling water has been collected and bottled at natural mineral springs for millennia, it was only in 1767 that Josephy Priestley, an English chemist, produced artificially carbonated water first by supending a bowl of water over a tank of fermenting beer (alcoholic fermentation produces as waste carbon dioxide), and then by dripping sulfuric acid into chalk and dissolving the gas into a bowl of water. Inventors like J.J. Schweppe and Anyos Jedlik took this process and commercialized it, producing early forms of soda water.
Today, soda water can be part of a dispensing gun (usually along with soft drinks), or be produced in a soda siphon, which relies on disposable pressurized carbon dioxide cartridges. Soda siphons are generally seen as a better solution than a soda gun, due to the real probability of off flavors being imparted by the lines that feed the gun.