What is a Lager?
Lager is a type of beer conditioned at low temperatures. Most lagers use a strain of yeast called Saccharomyces Pastorianus, a bottom fermenting yeast that works at colder temperatures—in contrast with to ale top-fermentation that works at warmer conditions.
Lager became prevalent in the beer world in the 19th century after the industrialization, due to the advance in refrigeration systems that allowed brewers to produce lagers all year round. Previously, lager brewing was reserved to winter months, while ale was used in summertime. The style has its origins in the areas of Franconia and Bohemia (nowadays Czech Republic).