Roulette is a casino game named after the French word meaning little wheel.
In the game, players may choose to place bets on either a single number, various groupings of numbers, the colors red or black, whether the number is odd or even, or if the numbers are high (19–36) or low (1–18).
To determine the winning number and color, a croupier spins a wheel in one direction, then spins a ball in the opposite direction around a tilted circular track running around the outer edge of the wheel.
The ball eventually loses momentum, passes through an area of deflectors, and falls onto the wheel and into one of 37 (single zero French/European style roulette) or 38 (double zero American style roulette) colored and numbered pockets on the wheel.
The first form of roulette was devised in 18th century France.
Many historians believe Blaise Pascal introduced a primitive form of roulette in the 17th century in his search for a perpetual motion machine.
The game has been played in its present form since as early as 1796 in Paris.
An early description of the roulette game in its current form is found in a French novel La Roulette, ou le Jour by Jaques Lablee, which describes a roulette wheel in the Palais Royal in Paris in 1796.
The description included the house pockets, "There are exactly two slots reserved for the bank, whence it derives its sole mathematical advantage." It then goes on to describe the layout with, "..betting spaces containing the bank's two numbers, zero and double zero". An even earlier reference to a game of this name was published in regulations for New France (Québec) in 1758, which banned the games of "dice, hoca, faro, and roulette".
The roulette wheels used in the casinos of Paris in the late 1790s had red for the single zero and black for the double zero.
To avoid confusion, the color green was selected for the zeros in roulette wheels starting in the 1800s.
In 1843, in the German spa casino town of Bad Homburg, fellow Frenchmen François and Louis Blanc introduced the single 0 style roulette wheel in order to compete against other casinos offering the traditional wheel with single and double zero house pockets.