know what cards are still in play - No more guessing;
improve your game;
works with any card game that is based on a single deck.
There are many methods to counting cards. Contrary to popular belief, none of them involves memorizing all the cards in the deck (Of course one cannot just start counting all the cards and remember them. This is Rainman stuff). Counting cards is a common practice among skilled blackjack players, and it is not illegal if you are able to perform the functions in your head. (I'm not encouraging you to do it).
Well, most people do not have the desire, time, or energy to do what it takes to become an expert card counter. Card Control helps you to remember what cards are still in play.
Warning: using a device to aid in the counting of cards is considered a felony under Nevada laws governing cheating... Although card counting is not illegal in many places, casinos still have the right to throw you out or disqualify you from playing the game. So, don't use Card Control to cheat.