Source: http://www.businessweek.com/articles/201...

Every major sports league in North America has a corresponding fantasy universe. To play, you select players from different real-world teams, and when your picks do well on the field (or court or rink), your make-believe team gets points. It started in the 1980s with baseball and football, mainly among friends who tracked stats in newspaper box scores. As fantasy leagues moved online, participation soared. More than 40 million people played fantasy sports in North America last year, the equivalent of 30 percent of U.S. adult males.

FanDuel, based in New York, brings a couple of twists to the game. The first is that leagues last only a day, so rather than wait all season to declare a winner, players know who won as soon as time runs out in the last game of the day. Twist two is money. Small-stakes fantasy leagues aren’t new, but FanDuel and similar sites bring it to a much larger scale. For a few bucks, a person drafts a team and competes against tens of thousands of others online. There are thousands of contests to enter each night for football, basketball, hockey, and baseball, whatever is in season. Like online poker, cash prizes can run to seven figures. Unlike online poker, it’s legal in most states.