Many of the examples in the book will center on simulations of a process with a number of moderately complex state changes. The card game of Blackjack involves a few rules and a few state changes during play. If you're unfamiliar with the game of Blackjack, here's an overview.

The objective of the game is to accept cards from the dealer to create a hand that has a point total that is between the dealer's total and twenty-one. The dealer's hand is only partially revealed, forcing the player to make a decision without knowing the dealer's total or the subsequent cards from the deck.

The number cards (2 to 10) have point values equal to the number. The face cards (Jack, Queen, and King) are worth 10 points. The Ace is worth either eleven points or one point. When using an ace as eleven points, the value of the hand is soft. When using an ace as one point, the value is hard.

A hand with an Ace and a seven, therefore, has a hard total of eight and a soft total of 18. This leads the player to choose to take extra cards. If the dealer is showing a face card, it's very likely the dealer is holding twenty points, and the player may not want to risk taking another card.

Each suit has four two-card combinations that total 21. These are all called Blackjack, even though only one of the four combinations involves a Jack. These combinations often provide a bonus payout, because there are only four of them available.

Most of the game is about proper choice of cards. There is, of course, a betting element. The distinction between playing and betting is made somewhat more complicated by the provision to split one hand into two hands. This is allowed when the player's two cards have the same rank. This option will be detailed in the next section on how the game is played.