Happy National Lager Day! As one of the most-sold styles of beer, lagers haven't been around all that long, comparatively. The bottom-fermenting yeast strain was first identified in the 19th century and required longer fermentations at colder temperatures. Brewers in medieval Bavaria noticed that their beers would continue to ferment throughout the winter while kept in dark caves. The German word "lagerbier" meant "beer meant for keeping."
For reference, ale yeast has been dated back to more than 5,000 years ago when it was used in ancient Babylon.
Feel free to hoist one up today in honor of lagers everywhere. Prost!