Straight: a single number. The chip is placed entirely on this square and no other.
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 edge between these numbers.
Street: a bet on three numbers on a single horizontal line. The chip is placed on the edge of the number at 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 these numbers.
Sixline (or 'sixaine'): a bet on two adjoining streets, with the chip placed at the corresponding intersection (as in 25-30).
Column: 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.

House Edge

The house average or house edge (also called the expected value) is the amount the player loses relative to a bet, on average. If a player bets on a single number in the American game there is a probability of 1/38 that the player receives 36 times the bet (35 times the bet plus the return of the bet itself), so the player ends up, on average, losing 5.26% on each bet:

( (probability * payout) / bet ) - 1 = expected value as fraction of bet

For example, betting $10 on a single number on an American wheel:

( ((1/38) * 360) / 10 ) - 1 = -0.0526

For European roulette: ( ((1/37) * 360) / 10 ) - 1 = -0.02703

The house has the same edge on all of the other kinds of bets, except for the five number bet where the house edge is considerably higher (7.89% on an American wheel) and the 'even money' bets in the European game, where the house edge is halved (only half the stake is lost on such bets when zero comes up).

The house edge should not be confused with the hold. The hold is the total amount that the house wins from a player. While the house might have an edge of 5.26%, if a player keeps playing until his or her bankroll is exhausted, the house will enjoy a hold of 100%.

Called (or Call) Bets

Traditional roulette wheel sectorsThere are a number of series in roulette that have special names attached to them. These are placed by betting a set amount per series (or multiples of that amount). They are based on the way in which certain numbers lie next to each other on the roulette wheel. Not all casinos offer these bets, and some may offer additional bets or variations on these.

Voisins du Zero ("Neighbours of Zero")

This is a name for the numbers which lie between 22 and 25 on the wheel including 22 and 25 themselves. The series is 22,18,29,7,28,12,35,3,26,0,32,15,19,4,21,2,25 (on a single zero wheel).

9 chips or multiples thereof are bet. 2 chips are placed on the 0,2,3 street; 1 on the 4/7 split; 1 on 12/15; 1 on 18/21; 1 on 19/22; 2 on 25/26/28/29 corner; and 1 on 32/35.

Tiers ("The third")

This is the name for the numbers which lie on the opposite side of the wheel between 27 and 33 including 27 and 33 themselves. The series is 27,13,26,11,30,8,23,10,5,24,16,33 (on a single zero wheel).

6 chips or multipes thereof are bet. 1 chip is placed on each of the following splits: 5/8; 10/11; 13/16; 23/24; 27/30; 33/36.

A variant known as "Tier 5,8,10,11" has an additional chip placed stright up on 5, 8, 10 and 11; and so is a 10-piece bet.

Orphelins ("Orphans")

These numbers make up the two slices of the wheel outside the Tiers and Voisins. They contain a total of eight numbers, the Orphans comprising 17,34,6 and the Orphelins being 1,20,14,31,9.

5 chips or multiples thereof are bet. 1 chip is placed straight-up on 1 and 1 chip on each of the splits: 6/9; 14/17; 17/20 and 31/34.

"xx and the Neighbours"

A number may be backed along with the 2 numbers on either side of it in a 5 piece bet. For example, "0 and the Neighbours" is a 5 piece bet with 1 piece straight-up on 3, 26, 0, 32 and 15. Neighbours bets are often put on in combinations, for example "1, 9, 14 and the neighbours" is a 15 piece bet covering 18, 22, 33, 16 with 1 piece; 9, 31, 20, 1 with 2 pieces and 14 with 3 pieces.

Any of the above bets may be combined, eg "Orphelins by 1 and Zero and the Neighbours by 1." The "...and the Neighbours." is often assumed by the Croupier.