The Beer Judge Certification Program lists 100 styles with defined ranges of alcohol by volume (ABV), bitterness (measured in IBUs, or International Bittering Units), and color (measured using SRM, or Standard Reference Method).Below is a series of charts for all 100 styles. Mouseover any style for more details and commercial examples. Rectangles to the top right corner represent beer that is high in alcohol and high in bitterness. In contrast, a rectangle in the bottom left corner represents a beer that is low in alcohol and low in bitterness.

Source: Charting All the Beer Styles | FlowingData