All other games rely on random occurrence in determining the outcome a roll of the dice, the spin of a roulette wheel, the revolutions of the reels on a slot machine. Each occurrence will be like the one before it and the one after dependent upon nothing, completely random, unpredictable, and infinite. However, blackjack exists in a finite world. Take a standard deck of 52 cards, and remove the four 7s and three of the four 5s. Each outcome is dependent on what has come before.
Every hand is different, and every round is a new event.
Even the first card dealt from a fresh deck can be one of 52. Then, once it is dealt, the odds are modified because it has been dealt. Therefore, to play to win at blackjack, you must know the principles of play in all these different scenarios. One of the earliest, and still one of the most popular treatise of blackjack is Edward O. Thorp's Beat The Dealer. Thorp, with the help of computers, discovered that certain situations called for specific play.