Betting is the wagering of something (often money) on a specific event with an unknown and uncertain outcome. This is done with the intent to win something of value, again, usually money. Betting requires that three factors are present: the amount or object that is wagered, the chance of winning, and the prize.
Sports betting is a form of wagering on who wins a sporting event. The intent of betting on a sport is almost always to win money. The probability of winning in is always, at best, an educated guess. There is always room for an upset, a withdrawal, or a disqualification within the world of sports.
The idea of betting or gambling dates back to at least 3000 B.C. when people used the first 6-sided dice in Mesopotamia. The very first sports bets were placed back in ancient Rome, on gladiator fights and chariot races. Bets could only be placed within the Roman community.
Sports betting as we know it didn't come into play until the 18th century. At that time, horse races started having more than two horses in them, and that's when the idea of betting on one of the horses appeared.
Finally, in the late 1800s, laws were established in the U.S. and Canada, preventing the mob from completely overtaking this industry. After that, very little was done in the betting world to keep the laws updated and established until the internet came into play.