Definition of dealer
The dealer is the person who deals the cards to the players at the table. To be precise, there are two types of dealer's: the real dealer who deals the cards to the players and the virtual dealer (dealer or button). In a casino poker game, the dealer will be the employee paid by the casino to shuffle the cards and deal them to the players at the table. He will also be the one who deals the flop, the turn, the river and moves the main prize pool to the winner in each hand. This "real dealer" will not play with the other players, he will be employed by the casino.
The virtual dealer or dealer or button
Unless you are in a friendly game, the player who is on the button position (also called dealer or dealer in French) will not deal the cards to the other players. His term of dealer will be symbolic. The dealer position in poker is the best possible position. It is the player just before the blinds who will have the privilege of speaking last on all streets post-flop (flop, turn and river). You can recognize the dealer by the "dealer" chip in front of it. Some people also talk about the brewer.