The gas commonly used in soda to make it fizzy is carbon dioxide (CO2). When carbon dioxide is dissolved in liquid under pressure, it creates carbonic acid, which gives soda its characteristic effervescence and tangy flavor. When the pressure is released, such as when you open a bottle or can, the carbon dioxide escapes, forming bubbles that rise to the surface. The carbonation not only enhances the drinking experience but also helps preserve the beverage. This fizzy quality is a defining attribute of carbonated drinks, enjoyed in various flavors and brands worldwide.