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).

Until the 19th century, the German word Lagerbier (de) referred to all types of bottom-fermented, cool-conditioned beer, in normal strengths. In Germany today however, the term is mainly reserved for the prevalent lager beer styles of southern Germany. In common parlance, these beers are distinguished by their colors, and referred to as a (Bavarian) "Helles" (pale), or a "Dunkel" (dark), though both words may be used as adjectives to describe other types of beer. The popular Pilsner style, which is more heavily hopped, although it is also a pale lager, is most often known as simply "Pilsner" (or "Pils") and generally is called neither a "Lagerbier" nor a "Helles". Numerous other types of lager-beer styles are produced, such as Bock, Märzen, and Schwarzbier.

In the United Kingdom, the term lager commonly refers specifically to pale lagers, many of which are derived from the Pilsner style. Worldwide, pale lager is the most widely consumed and commercially available style of beer. It is often known primarily by its brand name, and labeled simply as "beer".