Ales trace their heritage to the British and Belgian brewing traditions. Ale yeast ferments at relatively warm temperatures and at the top of the fermenting vessel. Lagers, which trace their heritage to German brewing culture, employ a yeast that works at cooler temperatures and at the bottom of the fermenting vessel. A period of conditioning follows fermentation. For lagers, this conditioning period takes place in a lager cellar, where the beer is stored at near-freezing temperatures for between four and 12 weeks, depending upon style.
Ales also condition at near-freezing temperatures for one to two days.
Whether it be lager or ale, the beer is then filtered to remove residual yeast and packaged in bottles or kegs. Some unique styles, such as traditional Bavarian weiss bier, are not filtered. The yeast remains in suspension giving it a cloudy opacity, rather than a sparkling brilliance.