The house edge is a percentage of each bet you make that the house takes in. It's regarded as payment for letting you play, like an entertainment tax. For the house to get this edge, winning bets are paid off at less than the true odds. Most machines are set to give you back 75 to 97 percent of the coins you put in, meaning the casino keeps 3 to 25 percent. Because of the randomness designed into the machines, your short-term results will vary substantially from play to play.
Many casinos offer both the American and European versions of roulette.
A European game won't have the 00 on the roulette wheel. When you have a choice between the two, always play the European version. Part of the card-shuffling ritual, cutting the cards divides the card decks in two so they can be reassembled in a different order. Bum cards are removed from the top of the deck and not played. The dealer inserts a cut card at the end of the deck as a reshuffling reminder so that the last hand doesn't run out of cards.