This article was taken from:
http://en.wikipedia.org/wiki/Online_poker

Online poker is the game of poker played over the Internet. It has been partly responsible for a dramatic increase in the number of poker players worldwide. Christiansen Capital Advisors stated online poker revenues grew from $82.7 million in 2001 to $2.4 billion in 2005,[1] while a survey carried out by DrKW and Global Betting and Gaming Consultants asserted online poker revenues in 2004 were at $1.4bn.[2] Traditional (or "brick and mortar", B&M, live) venues for playing poker, such as casinos and poker rooms, may be intimidating for novice players and are often located in geographically disparate locations. Also, brick and mortar casinos are reluctant to promote poker because it is difficult for them to profit from it. Though the rake, or time charge, of traditional casinos is often high, the opportunity costs of running a poker room are even higher. Brick and mortar casinos often make much more money by removing poker rooms and adding more slot machines. Online venues, by contrast, are dramatically cheaper because they have much smaller overhead costs. For example, adding another table does not take up valuable space like it would for a brick and mortar casino. Online poker rooms also allow the players to play for low stakes (as low as 2¢)[3] and often offer poker freeroll tournaments (where there is no entry fee), attracting beginners.