What's the difference between ales and lager?

What's the difference between ales and lager?

Jeff Evans (Freelance beer Writer) gives expert video advice on: How do beers from different breweries differ?; How do beers from different countries differ?; Why does the taste of beer vary so much? and more...

The world of brewing divides basically into two halves, ale brewing and lager brewing. It's all to do with fermentation and how the yeast reacts and how it works at the brewery. For ale fermentation, a yeast is used which tends to sit on top of the beer as it's fermenting. It also works at a warmer temperature, so you get more rounded, fuller, fruitier flavors, floral flavors perhaps coming off an ale fermentation. Lager fermentation uses a yeast which tends to sink to the bottom of the beer as it's fermenting it and works at much lower temperatures. With the other aspect of lager production, which is storing the beer for weeks, if not months, at very low temperatures so that the yeast continues to nibble away and round out the rough edges of the beer, that produces a crisper, cleaner flavor than you will get from an ale.