Lager

Lager (German:storeroom or warehouse) is a type of beer that is conditioned at low temperatures, normally in cold storage at the brewery, before being delivered to the consumer. It may be pale, golden, amber, or dark.

Although the defining feature of lager beer is its maturation in cold storage, it is also distinguished by the use of bottom-fermenting lager yeast. While it is possible to use lager yeast in a warm fermentation process such as with American steam beer, the lack of a cold storage maturation phase precludes such beer from being classified as lager beer. On the other hand, German Altbier and Kölsch, which use top-fermenting yeast and temperatures, but with a cold storage finishing stage, are classified as obergäriges Lagerbier (top-fermented lager beer).