A dealer deals the cards, manages bets and pays winners. In blackjack the dealer represents the house and must follow set rules, usually hitting on 16 or less and standing on 17 or more. Some tables make the dealer hit on soft 17, which raises the house edge. In poker, the dealer button marks the nominal dealer and moves each hand, even when a house dealer deals the cards. A dealer does not control the odds and cannot change the rules during play.
Example
A dealer showing 6 must keep drawing until the hand reaches 17 or more, so the dealer busts fairly often from a 6.