Blackjack became popular due to its engaging gameplay, straightforward rules, and strategic elements. Originating as "Vingt-et-Un" in 17th-century France, it evolved in the U.S. where it was renamed. The growth of Las Vegas in the mid-20th century played a crucial role in its popularity, as casinos promoted the game with favorable rules to attract players. The introduction of card counting techniques in the 1960s further enhanced interest, while the rise of online gambling in the late 1990s expanded accessibility, ensuring Blackjack's enduring appeal in both physical and digital casinos.