What is a burn card?
In formal card games, such as those played in casinos, a ‘burn card’ is a card dealt from the top of the deck stub, but discarded, or ‘burned’, unseen and unused by the players. Burning a card before each round of betting is intended as a deterrent against illegally altering playing cards, by bending, nicking or otherwise marking them, so that their value and suit can be determined without seeing the face of the card.
In poker variants, such as Texas Hold’em and Omaha Hold’em, that use community cards, knowledge of the next community card is obviously extremely valuable. Consequently, before dealing the flop, turn and river the dealer deals a burn card, face down, next to the discard pile, or ‘muck’. Even in the event of marked cards, players cannot see the next community card until immediately before it is dealt, so have little or no time to take advantage of any markings. Without a burn card before each round of betting, a marked card could be lying, in plain view, at the top of the deck stub for the whole of the previous round, allowing players ‘in the know’ an unfair advantage over their fellow competitors and/or the house.
Of course, in a modern casino, any attempt at card marking is unlikely and, unless highly sophisticated, will probably be discovered sooner rather than later in any case. Nevertheless, burn cards are retained in bricks-and-mortar casinos as a matter of custom or tradition.