Bock is a strong lager, which has origins in the Hanseatic town Einbeck, Germany. The name is a corruption of the medieval German brewing town of Einbeck. The original Bocks were dark beers, brewed from high-coloured malts. Modern Bocks can be dark, amber or pale in colour. Bock was traditionally brewed for special occasions, often religious festivals such as Christmas, Easter or Lent.
Bocks have a long history of being brewed and drunk by Roman Catholic monks in Germany. During the Spring religious season of Lent, monks were required to fast.
In the twentieth century, bock beers gained an undeserved reputation (primarily in the United States) for being brewed from the dregs of previous brewings. This is impossible, as the "dregs" were not clearly defined and the leftovers from the brewing process are not fermentable. The rumour may have started because some brewers used inferior ingredients or a large quantity of adjuncts in their bocks. (Full article...)