Where did it all start?
Nobody really knows the origin of Blackjack. There is debate about whether it originated from Italian or French games which both had similar aspects.
The Italian game Thirty One dates all the way back to the 1400's and involved the player getting three cards with the objective of getting as close to 31 as possible. Seven and a Half also originated in Italy in the 1600's. The game takes cards between 8 and 10 out of the deck. Cards between 2 and 7 all count as their face value, face cards (Jacks to Kings) count as 1/2, and aces count as 1. Seven and a Half was played against a dealer and involved trying to get as close to 7 1/2 points without going over, making it very similar in gameplay to Blackjack.
However the French also have a claim to Blackjack with their game Vingt En Un which directly translates to "twenty-one" and originated in the 1600's as well. The point of the game was to reach 21 in the same way as Blackjack today. In fact the name Blackjack came from the best hand in Vingt En Un which involved getting an Ace and a Jack of Spades. Players also bet after each round rather than placing their bet all at the beginning like they do in Blackjack.
Migration to America
As you can see, card games involving different aspects of today's Blackjack had been played for hundreds of years in Europe before Blackjack became popular in America. In 1789, the French Revolution ended and Vingt En Un migrated to the United States where card games were legal. It became very popular, but gambling came under attack throughout the early 1800's from lawmakers and the public. Eventually, in 1860, all games in which the player bet against the house were made illegal. Blackjack was forced underground and continued to evolve into the game we play today.
In 1931, Nevada legalized gambling and Las Vegas was created. Blackjack made its way back out of underground America and back into a legal game loved by millions of Americans. Books on card counting and Blackjack strategy were published in the late 1940's and 1950's as more and more gamblers looked for any edge against the house.
Blackjack is played in casinos all over the world. It is also played online by millions of people every day. There are a few variations regardinging the number of decks and the payouts for Blackjack, but the strategies remain mostly the same and are vital to success in all types of Blackjack.