Beer comes in literally hundreds of varieties. But, as a rule, all beer is either an ale or a lager. Here are some basic generalities.
Stout: (such as Guinness)
Dark, thick, and nasty; outstanding stuff. Most stouts have a roasted barley addition that infuses a rich flavor such as coffee.
Basic English Ale: (such as Bass)
Typically more hearty than lagers, sometimes bitter and strong. A good one melts in your mouth and leaves a pleasant aroma that hovers in the air. I try to pair bold ale with a barstool and an empty afternoon.
Hefeweizen: (such as Paulaner)
These beers have a cloudy appearance due to unfilered yeast and the addition of malted wheat. Make sure to get every last drop; that's where the flavor is.
Medium-Bodied Lager: (such as Harp Lager)
Usually lighter and cleaner tasting than ales. Lagers ferment slow and cold, producing a crystal clear, bubbly beverage that tickles your tongue.
American Larger: (such as Budweiser)
Very light in color, high carbonation. This is what we Americans typically drink at football games and cookouts. You probably have a six-pack in your fridge now.