What is the most dominant beerstyle in the world? That's right Pilsner. Back in the day light/pale beers were not available. In Munich the lagers were darker. The light pilsners from Bohemia were all the rage. Brewers needed to compete and so the brewers from Munich developed a new style in response, Munich Helles.
Pilsner Urquell, the original Pilsner, became so popular that the style took it's name. This beer was first copied by the Germans (German Pilsner), German brewers migrated to the United States bringing their beer and brewing style with them and thus we have the Classic American Pilsner. Not to stop there the Standard and Premium American Lagers, followed by Lite American Lager and most recently by the style of Imperial Pilsner.
Why was this beer developed by the Bohemian brewers? Bad Beer!!! the same thing that drives us to make better beer. In 1838 the brewers of Pilzen rolled 36 barrels of ale out into the streets and dumped them because they were undrinkable. They decided that they wouldn't let this happen again. They hired a Bavarian brewer to teach them the new "German" brewing style lagering. Rumor has it that a couple of years later a monk smuggled some German Lager yeast to Pilzen. The rest, as they say it, is history.
History: First brewed in 1842, this style was the original clear, light-colored beer.
Aroma: Rich with complex malt and a spicy, floral Saaz hop bouquet. Some pleasant, restrained diacetyl is acceptable, but need not be present. Otherwise clean, with no fruity esters.
Appearance: Very pale gold to deep burnished gold, brilliant to very clear, with a dense, long-lasting, creamy white head.
Flavor: Rich, complex maltiness combined with a pronounced yet soft and rounded bitterness and spicy flavor from Saaz hops. Some diacetyl is acceptable, but need not be present. Bitterness is prominent but never harsh, and does not linger. The aftertaste is balanced between malt and hops. Clean, no fruity esters.
Mouthfeel: Medium-bodied (although diacetyl, if present, may make it seem medium-full), medium carbonation.
Overall Impression: Crisp, complex and well-rounded yet refreshing.
Comments: Uses Moravian malted barley and a decoction mash for rich, malt character. Saaz hops and low sulfate, low carbonate water provide a distinctively soft, rounded hop profile. Traditional yeast sometimes can provide a background diacetyl note. Dextrins provide additional body, and diacetyl enhances the perception of a fuller palate.
Commercial Examples: Pilsner Urquell, Krušovice Imperial 12°, Budweiser Budvar (Czechvar in the US), Czech Rebel, Staropramen, Gambrinus Pilsner, Zlaty Bazant Golden Pheasant, Dock Street Bohemian Pilsner
Ingredients: Soft water with low mineral content, Saaz hops, Moravian malted barley, Czech lager yeast.
Source: BJCP: http://www.bjcp.org/course/Class2Lesson2Pilsners.php, http://www.bjcp.org/2008styles/style02.php