Card counting is a method for controlling the odds in blackjack by varying your bets as the deck becomes more or less favorable for the player. Casinos prefer this to be a game of chance than a game of skill though card counting is not illegal in most locales. It becomes illegal when you start counting with the help of a device. If you are a casual player, then card counting is tough unless well-planned can give way for the casino to discover. Once they know that you are counting, and then a quick shuffle will removes any edge. Now this has been taken care of by technology. Nevada gambling regulators have warned casinos of a card-counting program that works on Apple iPhone and iPod. The program is iBlackjack.

It is designed for use on the iPhone/iPod touch. You can play against the house, complete with Vegas rules including double downs, splits and surrender. Because of popular request card-counter has also been added. But since card-counting is not illegal, it can still get you thrown out of a real casino. And since casinos use multiple decks, the value of card counting is diminished.
[Gearlog]