To determine the winning number and color, a croupier spins a wheel to determine winning number and color in one direction, then spins a ball in the opposite direction. The ball eventually loses momentum and falls on to the wheel and into one of 37 (in European roulette) or 38 (in American roulette) colored and numbered pockets on the wheel.
The pockets of the roulette wheel are numbered from 1 to 36, alternating between red and black. There is a green pocket numbered 0 (zero). In American roulette, there is a second green pocket marked 00.
Betting system in Roulette:
• Straight-up: a single number bet. The chip is placed entirely on the middle of a number square.
• Split: a bet on two adjoining numbers, either on the vertical or horizontal (as in 14-17 or 8-9). The chip is placed on the line between these numbers.
• Street: a bet on three numbers on a single horizontal line. The chip is placed on the edge of the line of a number at the end of the line (either the left or the right, depending on the layout).
• Corner (or square): a bet on four numbers in a square layout (as in 11-12-14-15). The chip is placed at the horizontal and vertical intersection of the lines between the four numbers.
• Six Line: a bet on two adjoining streets, with the chip placed at the corresponding intersection, as if in between where two street bets would be placed.
• Trio: a bet on the intersecting point between 0, 1 and 2, or 00, 2 and 3.
Outside bets typically have smaller payouts with better odds at winning.
• 1 to 18: a bet on one of the first low eighteen numbers coming up.
• 19 to 36: a bet on one of the last high eighteen numbers coming up.
• Red or Black: a bet on which color the roulette wheel will show.
• Even or Odd: a bet on an even or odd number.
• Dozen Bets: a bet on the first (1-12), second (13-24), or third group (25-36) of twelve numbers.
• Column Bets: a bet on all 12 numbers on any of the three vertical lines (such as 1-4-7-10 on down to 34). The chip is placed on the space below the final number in this string.