Sour beer is a type of beer that has a tart, tangy flavor, often resulting from wild yeast and bacteria during fermentation. This style can include various subtypes, such as Berliner Weisse, Gose, and Lambic, each with unique characteristics. The sourness can range from mild to intense, appealing to those who enjoy complex flavors. The souring process typically involves using lactic acid bacteria or wild yeasts like Brettanomyces. These microorganisms create a range of flavors and aromas, making sour beers distinct from traditional styles. Many craft breweries experiment with souring techniques, contributing to the growing popularity of this beer category.