Lagers stem from the German word “lagern” meaning to store. Lagers are made with a bottom or cold-fermenting yeast that sinks to the bottom of the brew during the fermentation process, typically at 46 to 55 degrees Fahrenheit. Traditionally, lagers need to age before their brewing process is complete.
Their brewing time can increase to a month or more. A longer, cooler fermentation process inhibits the production of esters (which gives beer a more fruity taste) and other fermentation by products common in ales.
The lager beers are often cleaner, smoother, crisper, and mellower. Castle Lager is a prime example of a great lager served cold.