soda water
Water filled with bubbles from added gas, not sweetened.
Soda water is water that has been infused with carbon dioxide gas under pressure, creating bubbles and a fizzy, slightly tart taste. When you open a bottle of soda water, you hear that satisfying psssht sound as the pressurized gas escapes, and you see bubbles rising to the surface.
The process was invented in the late 1700s, when scientists figured out how to artificially create the natural carbonation found in certain mineral springs. Before then, people had to travel to special springs to enjoy naturally fizzy water.
Soda water forms the base for most soft drinks: add syrup and flavoring to soda water and you get cola, root beer, or lemon-lime soda. But plain soda water has no sweeteners or flavors, just the clean, crisp taste of fizzy water. Some people drink it by itself, while others use it to make drinks sparkle.
You might also hear it called carbonated water, sparkling water, club soda, or seltzer. These terms are mostly interchangeable, though club soda usually contains added minerals that give it a slightly different taste.