I'd wager most you readers know how to deal a hand of Texas Hold'em, but apparently not everyone knows that there is a reason behind why we deal like we do. In this case, the purpose of the burn card. Beginners may think it is just out of tradition that a card is burned (or discarded) before the reveal of community cards. Perhaps they just never thought about it. Chances are you know better, but if not, allow me to educate.
After the hole cards are dealt and the players are contemplating the strength of their hands, the deck is typically out there for all to see. In the event of a marked deck, the back of the card gives away as much information as the front. Poker players, being the suspicious lot that they are, invented the burn card to take the card in question out of play. After the flop, the same deck visibility applies, so before the turn there is a burn card and likewise for the river.
How do I know other players don't get this? The example here is a peeve of mine that has made itself apparent on too many occasions. The player on the button deals out the hands as normal then immediately burns the following card and sets the deck down. Pre-burning is completely useless and missing the point. An even better example is the amateur who burns and sets aside all the community cards in advance, usually proud of his more efficient approach to dealing.
This tidbit is another illustration of when knowing the "whys" of life are more important than knowing the "hows." It is sometimes in the best interest of a good player to keep a bad player in the dark, but please, if you see someone making these kinds of mistakes it is in the best interest of everyone to say something. Knowing is half the battle.