The global online gambling market is a complex area. Legislation not only differs country to country, but in the case of the USA, differs from state to state.
The UK leads the way in terms of revenue, with an estimated £2.5bn wagered online in 2013 - with the sports betting market growing 79% since 2009. Many of the largest European bookmakers are based in the UK, or have originated here, the likes of William Hill, Bet365, Ladbrokes and Coral. Whilst many mainland European countries have relaxed legislation, there are still a number who have not.
Consumer expenditure on online gambling and betting broke through the £2.5 billion barrier in 2013, as many of the leading operators continue to record double-digit revenue growth.Stickyeyes, Online Gambling and Betting Intelligence Report 2013
The United States represents the most potential as a lucrative market for online gambling. Whilst gambling is legal under US federal law, with individual states free to regulate or prohibit the practice, there are significant restrictions relating to interstate and online gambling
During 2012, over one-third (34% circa. 71 million people) of the US adult population over the age of 21 visited a casino.ibid
The two largest prospective markets in Asia - China and South Korea, remain closed to online gaming. Whilst it's legal to gamble in Macau, this only covers land based activity. Japan bans most forms of gambling with the exception of lotteries and racing bets, although recently there has been some relaxation.