No matter how you choose to gamble, whether it be land based or online, you should understand how the casino makes money on your visit. They make money on you by the simple fact that they do not pay out the actual odds for the game you play.

Say, you flip a coin, your chances of heads or tails is equally 50/50. Even money would be made if someone paid you one dollar each time you were wrong and the same each time you were right. In the long run, you wold just break even. But in a casino, the odds would vary for each game and that way they can make money off your bet. It would be like they paid you 95 cents for each time you were right. That is where they make their slight income.
Remember the card game you played as a kid called War? That came is now played in Las Vegas. You play against the dealer and with each dealing of cards if you card is higher, you win and vice-versa. But, with this game, and the way they can make money is, if both dealt cards are the same, you choose to either surrender or you go to war. Here you must make the same size bet as your original. You win, you ONLY get paid out your original bet, if you lose, they dealer gets both bets.