A Blackjack Croupier is a man or woman who is in charge of dealing the cards and running the gaming table. This is the person that you are playing against when you play Blackjack, as he or she will be responsible for the moves that the house makes. This does not make them the opponent, really, since the house has a prescribed way of doing things that the croupier knows and follows. You are not so much playing the croupier as you are playing the odds and the house deck. You do not always need to know how to read the croupier the way that you would need to read a different player in a game of poker. Blackjack is not that kind of a game. All you are doing is seeing how close you can get to twenty-one and then betting that it is close enough. If the croupier busts or beats you, it is not so much because of something that he or she did, but because of the way that the cards fell.
That being said, individual croupiers may have different tendencies and strategies. The house does have to decide if it is going to hit or stand once it reaches a certain point. Some casinos have rules and regulations for their croupiers to make sure that they all do things the same way. They have worked out the odds and know what they will be doing at all times — for instance, some casinos may tell their croupiers to always hit on sixteen or to always stand. If there are not set standards, however, you may be able to figure out what a certain croupier does when he or she is looking at a certain pairing of cards, and make your bets accordingly.
The difference is that the croupier gets to go after you do. He or she can see what you have and what needs to be beaten in order for the house to win. Also, you can only see one of the house cards, and so can the croupier. This makes it very hard for the croupier even to have a tendency, since he or she does not even know what is held in the house hand until you have already played.