Blackjack, or "21", has a long and complex world history. It is widely believed that the game originated in Spain, mainly because Miguel de Cervantes recorded the first written reference to the game in a short story. Then the game is called "Veintiuna", or "21".
In order to increase the player's interest, the fledgling casino (called the casino) attracts players to the table with bonuses and favorable odds - one such bonus is a 10 to 1 bonus on the hand containing the spades and black jack, what? It was quickly called "blackjack."