What is the difference between ale and lager?

The distinction between ale and lager primarily lies in the type of yeast used and the fermentation temperature. Ales are indeed fermented with top-fermenting yeast strains, specifically Saccharomyces cerevisiae. This yeast is most effective at warmer fermentation temperatures, typically ranging from 60°F to 75°F (15°C to 24°C). This process allows ales to develop more complex flavors and aromas in shorter fermentation periods.

On the other hand, lagers are brewed with bottom-fermenting yeast, specifically Saccharomyces pastorianus, which ferments at cooler temperatures, usually between 45°F to 55°F (7°C to 13°C). This cooler fermentation process produces a cleaner, crisper flavor profile and usually requires a longer maturation period.

The correct answer captures this fundamental aspect of brewing methods, highlighting the role of yeast and temperature, which is essential for understanding the basic differences between these two major categories of beer. Recognizing this provides a solid foundation for further exploration of beer styles and brewing techniques.