beeradvocate.com - Beer Styles - Two categories of beer exist: ale and lager. Underneath each category are the styles.
We brew ales. Some style names, however, include the word "ale", which may confuse things. That usage refers to the yeast type. But technically, all the beers that we brew are ales because of the fermentation process.
From the beeradvocate.com Styles page:
What's an Ale?
This category of beer uses yeast that ferments at the "top" of the fermentation vessel, and typically at higher temperatures than lager yeast (60-75F), which, as a result, makes for a quicker fermentation period (7-8 days, or even less). Ale yeast are known to produce by-products called esters, which are "flowery" and "fruity" aromas ranging, but not limited to apple, pear, pineapple, grass, hay, plum, and prune.
What's a Lager?
The word lager comes from the German word lagern which means, "to store". A perfect description as lagers are brewed with bottom fermenting yeast that work slowly at around 34 degrees F, and are often further stored at cool temperature to mature. Lager yeast produce fewer by-product characters than ale yeast which allows for other flavors to pull through, such as hops.