The legality of online gambling has been questioned by the federal government. The case of United States v. K23 Group Financial Services focuses on money laundering and 18 U.S.C. 1955 violations. However, some states have already legalized online gambling. These states are now moving forward with regulating the online gambling industry.

Legality of internet gambling is disputed, and laws differ state-by-state. The Unlawful Internet Gambling Enforcement Act of 2006 limits banks from transacting with illegal internet gambling sites, but does not define what constitutes a legal internet gambling site. While it was commonly believed that the Federal Wire Act prohibited all forms of online gambling, this law does not apply to online casinos, lottery sites, or poker sites.

There are two main types of online casinos: download-based and web-based. The former requires the installation of a software client that connects to the online casino service provider. These casinos run faster than their web-based counterparts because the software client caches sound programs and graphics. However, downloading software from the internet can be time-consuming and carries a risk of malware.