A free spin is essentially an offer that a casino gives to its players to spin the reels free of charge and have the opportunity to win real cash. The free spins may be given to both new and current customers, and it's one way to reward and encourage them to continue betting.
The United States is the land of freedom and opportunities. Besides that, it's also where one can easily play casino games by joining many online mobile casinos that cater to US residents. If one doesn't have the chance to go to Las Vegas, online gambling allows them to enjoy their favorite games without leaving their home.