Is beer carbonated?

Beer is carbonated and the gas, carbon dioxide, comes from one of two sources. The first source is natural, while the second is introduced to the fermented liquid.

Depending on the beer or the brewery, carbonation results from the natural fermentation of yeast cells on sugar molecules that produce alcohol and the gaseous byproduct. An alternative is to inject a finished beer with carbon dioxide. The advantage of the latter is a crystal clear product, while the former may exhibit sediment. The bubble size is also different; the injection process produces larger bubbles than the finer bubbles that result from fermentation.