Modern ginger beer is a sweetened and carbonated, usually non-alcoholic beverage, a type of soft drink. Historically it was a type of beer brewed by the natural fermentation of prepared ginger spice, yeast and sugar. Modern ginger beers are often manufactured rather than brewed, frequently with flavour and colour additives, with artificial carbonation. The related ginger ales also are not brewed.

Ginger beer is still produced at home using a type of symbiotic colony of yeast and Lactobacillus bacteria (SCOBY) known as a "ginger beer plant", or from a "ginger bug" starter created from fermenting ginger, sugar, and water.

Brewed ginger beer originated in Yorkshire in England in the mid-18th century and became popular throughout Britain, the United States, Ireland, South Africa, the Caribbean and Canada, reaching a peak of popularity in the early 20th century.

Brewed ginger beer originated in the UK, but is sold worldwide. It is usually labelled "alcoholic ginger beer" to distinguish it from the more established commercial ginger beers, which are often not brewed using fermentation but carbonated with pressurized carbon dioxide, though traditional non-alcoholic ginger beer may also be produced by brewing.^{[better source needed]}

Non-alcoholic ginger beers are made by brewing, followed by heating to reduce alcohol content to below 0.5% ABV, below which beverages are legally classified as "non-alcoholic" in many jurisdictions. Ginger beer can be served by itself or as part of a cocktail. Ginger beer is more strongly flavoured with ginger and less sweet compared to ginger ale.

The ginger beer soft drink may be mixed with beer (usually a British ale of some sort) to make one type of shandy, or with dark rum to make a drink, originally from Bermuda, called a Dark 'N' Stormy. It is the main ingredient in the Moscow Mule cocktail, though ginger ale may be substituted when ginger beer is unavailable.

Ginger beer plant (GBP), a form of fermentation starter, is used to create the fermentation process. Ginger beer was defined by Harry Marshall Ward as “beverage containing a symbiotic mixture of yeast and bacteria, and containing sufficient amounts of nitrogenous organic matter and beet sugar or cane sugar in its aqueous solution”. The GBP was first described by Ward in 1892, from samples he received in 1887.

Also known as "bees wine", "Palestinian bees", "Californian bees", and "balm of Gilead", it is not a plant but a composite organism comprising the yeast Saccharomyces florentinus (formerly S. pyriformis) and the bacterium Lactobacillus hilgardii (formerly Brevibacterium vermiforme), which form a symbiotic culture of bacteria and yeast (SCOBY). It forms a gelatinous substance that allows it to be easily transferred from one fermenting substrate to the next, much like kefir grains, kombucha, and tibicos. Original ginger beer is brewed by leaving water, sugar, ginger, optional ingredients such as lemon juice and cream of tartar, and GBP to ferment for several days, converting some of the sugar into alcohol. GBP may be obtained from several commercial sources. Until about 2008 laboratory-grade GBP was available only from the yeast bank Deutsche Sammlung von Mikroorganismen und Zellkulturen in Germany (catalogue number DMS 2484), but the item is no longer listed. The National Collection of Yeast Cultures (NCYC) had an old sample of "Bees wine" as of 2008^[update], but current staff have not used it, and NCYC are unable to supply it for safety reasons, as the exact composition of the sample is unknown.