Beer can fundamentally be divided into two basic types: ales and lagers.  The brewing methods and ingredients for ales and lagers are very similar with the big exception being in the kind of yeast used to ferment the beer.

Ale, in one form or another, has been brewed since ancient times.  For a long time ales were produced from malted grains (particularly barley), were without carbonation and were flavored and preserved with various herbs and spices.  In the 15th Century hops were introduced to England from the Netherlands and became one of the key ingredients used by ale brewers.  Not only did the hops add bitterness, flavor and aroma to the brew, but they also acted as a natural preservative to help keep the beer palatable longer.  While ales have been brewed all over the world, England has long been the major producer and consumer of a wide variety of ales.

Ales use top fermenting yeasts (ex. Saccharomyces cerevisiae) that typically ferment best at temperatures between 60-70 degrees Fahrenheit. The relatively high temperature leads to a quick fermentation which helps to produce the complex tastes and smells that ales are known for.  Ales tend to be a little sweet, relatively full bodied and can be anywhere from pale straw to dark roasted coffee in color depending on the grains used to brew them.  Due to the higher fermentation temperatures and more forgiving styles, ales are very easily brewed by the home brewer.  Since home brewing was federally legalized in 1978, ales have enjoyed a resurgence of popularity in the United States and continue to be poplar with craft breweries as well as home brewers.   

Read about Ale Styles.

If England is thought of as the capital of ale, then Germany is at the heart of lager.  In fact the word lager is a German word for storage.  Germany has a long tradition of beer brewing and like other countries produced a variety of ales.  German brewers would brew batches of ale in late spring and store it all summer in cool, dark caves.  When fall rolled around the beer was brought of the caves and the resulting product was a crisper, smoother beer.  It is thought that overtime there was a spontaneous mutation in the yeast that caused it to perform better at lower temperatures.  When the new strain of yeast was isolated and propagated the lager style of beer was born.

Lagers use bottom fermenting yeast (ex. Saccharomyces uvarum) that ferments at much lower temperatures than ale yeast.  Since the temperatures at which lagers ferment is so much lower (typically between 38-50 degrees Fahrenheit) the fermentation takes significantly longer.  The slower, more methodical fermentation helps give lagers the clean, crisp taste that they are know for.  After the prolonged fermentation is complete, the brew is then aged at low temperatures in a process called lagering.  Lagering helps to clarify the beer and to allow it to mellow and age.  Once refrigeration technology allowed brewers to lager in factories rather than caves, lager production exploded and became the beer of choice for much of the world.  Due to the difficulty in regulating the temperature of the fermentation and lagering processes many home brewers do not attempt brewing lager beers without specialized equipment and a reliable refrigeration source.  Also, because of their typically clean taste and crystal clear appearance, lagers do not hide flaws well and can quickly expose poor brewing techniques.  However, any home brewer with money to spend and the will to succeed can readily produce a quality lager at home.

Read about Lager Styles.