If I walked into a casino and started playing blackjack, my opponent is the casino. Like roulette and many other casino games, I am playing against the house. In theory bad luck could cause the casino to lose money on any given night. Although, I doubt this ever happens seeing that these games keep the odds in favor of the house.
From the casino's point of view, including poker rooms is an even safer bet. The players compete against each other rather then the house. The casino has no sake in whether Player X wins or loses. The casino wins either way. Some percentage of the pot or some fee for playing goes to the casino for hosting the game and providing the dealers. This is the rake. Internet poker rooms operate the same way. Their rakes are usually low, but then they have fewer expenses.
This is something you may know, but also something that is important to consider if you are thinking about making the jump from your home games to casino play—on-line or live. It is not good enough to break even. You break even, you lose.
In addition to that, you need to go in knowing that the minimum buy-ins and blinds will probably be higher then your home games. It may be higher than you are comfortable playing. I have known a few friends who came in with an amount in their head that they expected to risk on their first trip to a casino and lose twice that with in the first 15 minutes.
Your first trip to a casino can be a thrilling experience, but it is also intimidating. My advice to you is to look up buy-in costs before hand, build up a bankroll that you can afford to lose and is sufficient enough to be at least an average stack at the table. Walk in with nothing to prove and play solid poker.