酸啤酒, or "sour beer," is a type of beer that has a tart or sour taste, which is achieved through specific fermentation processes. This style often uses wild yeast strains, such as Brettanomyces, or bacteria like Lactobacillus and Pediococcus. These microorganisms produce lactic acid, contributing to the beer's unique flavor profile. Sour beers can vary widely in taste, ranging from mildly tart to intensely sour. They are often enjoyed by craft beer enthusiasts and can be found in various styles, including Berliner Weisse, Gose, and Lambic. The complexity of flavors makes sour beers a popular choice for those seeking something different from traditional lagers and ales.