I like playing blackjack, I might go to a casino one day and try to win a lot of money.
I've played blackjack before.  It is also known as twenty-one. All the players compete against the dealer. 
How long has it been around for?
Good question.  I have no idea. But there are different ways of playing it around the world. In the U.S. the dealer is dealt two cards.  One up and one down.