Carbontated drinks, often called sodas, can vary in the exact types of elements and ingredients they contain. It all depends on the type of drink. Simple drinks like seltzer are basically carbonated water alone, while flavored drinks can contain many other elements as either flavors or preservatives.
Carbonated water contains carbon dioxide. Before water is carbonated, it is first "de-aired," removing all air from the water container. The water is then chilled and the carbon dioxide is injected and dissolved into the water under high pressure. In most cases, especially when it comes to flavored and sweetened drinks, the water is not carbonated until after all other ingredients are added.
The other ingredients in these drinks can vary, but there are similarities based on the general type of drink. Chocolate-based sodas like Coca-Cola, Pepsi and Dr Pepper often contain phosphoric acid and caramel color. Lemon-lime sodas like Sprite often have citric acid. Ingredients that contain benzoate are commonly used as preservatives in soda. Natural flavors are also used, especially in drinks that include a specific flavor like cherry or vanilla.
Most sweetened carbonated soft drinks use high-fructose corn syrup. This substance replaced sugar around the 1980s because it was less expensive. Since its inception, however, nutrition experts and other groups have criticized the use of corn syrup, claiming it to be more addictive and fattening. In 2010, Pepsi released a number of "throwback" drinks that used sugar. Diet soft drinks use artificial sweetener, and the exact type of sweetener often changes. depending on what is considered the safest type.
A number of carbonated drinks are known for also being caffeinated. This is especially true of the chocolate-based drinks. The caffeine primarily comes from cocoa and coffee beans, though the drug itself is what's specifically listed on the ingredients. Caffeine is known for being a mild stimulant that accelerates the nervous system and heart rate, although it is the body itself that directly does this while the caffeine blocks the body's regulators.