coan.net: There are various ways. A house can take a percentage of the buy-in, or a percentage of the pot (sometimes capped at a maximum). Or it can take fixed fees. For instance, having the dealer pay a fee each round, or asking a fixed fee of every player every X minutes. Or they organize tournaments, and ask an entrance fee of all the participants. The difference between the sum of the entrance fees and the prize money is the rake of the house. Or the casino makes it money through other means, and uses poker to attract people that spend their money buying expensive drinks or something else.