Blackjack has been influenced by other card games like Vingt-et-Un and Pontoon. Vingt-et-Un, a French predecessor, introduced foundational elements such as the goal of reaching 21 points without busting and the concept of hitting or standing. Pontoon added variations, such as the player acting before the dealer reveals their hand and unique terminology, like calling a natural 21 a "Pontoon." These influences have shaped the rules and strategic aspects of modern blackjack, balancing luck and skill in a competitive gaming environment.