Wheat beer is a beer that is brewed with both malted barley and malted wheat, rather than only barley. The addition of wheat lends wheat beers a lighter flavor and paler color than most all-barley ales. Wheat beer is customarily top fermented, that is, fermented with ale yeast.
Wheat beers have become very popular in recent years, and are especially popular in warm weather.
The first picture is a draft wheat beer in its traditional German glass. Your server should present it to you with a lemon wedge on the rim. Enjoy the unique banana nose and flavor and then squeeze the lemon in for another dimension.
The second pic is my favorite German imported wheat beer, König Ludwig Weissbier. When you pour one of these, leave a little beer in the bottle to swoosh around and suspend the yeast sediment on the bottom. Taste the beer first and then add the yeast for even more flavor. Here's a five-star review that agrees with me on this beer.
American microbreweries have gotten in on the wheat beer act with some respectable entries. Below are pics of three I will drink when I can't find the König: Pyramid Hefe Weizen (hefe means with yeast sediment; weizen or weiss is wheat); Harpoon's UFO Hefeweizen; and Sierra Nevada Wheat Beer. Enjoy!
UPDATE: I cannot get König Ludwig this year but am now ready to say that Paulaner Hefe-Weizen from Germany has a delicious banana nose. Try it. I also sampled two more American efforts: Anchor Summer Beer, which is a filtered wheat beer, and Flying Dog's In-Heat Wheat, which is a nice hefe.