Daily Fantasy Sports (DFS) represent a variation of fantasy games tied to sports. Analogous to classic fantasy sports, players pit against each other by forming a roster of professional athletes specific to a league or contest, sticking under a salary cap, accumulating points based on the actual statistical performance of the chosen athletes during authentic worldwide events. DFS constitute an expedited format of traditional fantasy sports that are engaged in over concise periods, for instance, a week or a single day as opposed to those extending over the span of a season. DFS are usually organized as paid competitions, usually termed "contests"; victors get to part of a pre-agreed pot which is funded through their entry fees. A slice of the entry fees goes to the provider in the form of rake revenue.

In the United States, the DFS industry predominantly had two rivals: FanDuel based in New York, and DraftKings originating from Boston. Both firms began as startups backed by venture capital, received capital from investor companies, sports commentators, leagues, and team proprietors, and gained fame through their assertive promotional endeavors. As of September 2015, the two entities had an estimated worth of at least $1 billion and controlled 95% of the U.S. DFS market. Their competition was mainly lesser DFS services, including Fantasy Aces and Yahoo! Sports. The daily fantasy style's popularity has been attributed to its ease compared to the season-long games, along with the emphasis on sizable money prizes in the promotional campaigns. Additionally, DFS are credited with enhancing the TV audience and involvement with sports.

DFS faced condemnation due to its parallels to sports wagering. Several U.S. states declared that DFS matches comprised betting and sports gambling, which was majorly illicit in the majority of states under the Professional and Amateur Sports Protection Act of 1992, asserting that their elements of luck surpassed those of skill or the degree of control a player had on the game's results. A state lawsuit from New York, spurred from a probe into claims that DraftKings and FanDuel workforce had utilized internal data to gain cash rewards from each other, sparked vindictive legal suits from these firms. They contested that the judgments were a miscomprehension of their services' essence. By December 2017, 18 states, including Massachusetts and Virginia, declared DFS was a permissible game of skill.

Becoming largely irrelevant in the U.S., these concerns were brushed aside in 2018, when the Professional and Amateur Sports Protection Act of 1992 saw its demise in the Supreme Court lawsuit, Murphy v. National Collegiate Athletic Association. With the green light for states to legalize betting on sports, DraftKings and FanDuel subsequently expanded their scope adding the function of bookmakers to leverage their pre-existing customer base and legal proficiency, while FanDuel agreed to be taken over by Irish firm Paddy Power Betfair, becoming its primary U.S. subsidiary.

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