In Texas hold'em and Omaha it is the first 3 board cards to be dealt face up (at the same time) after all players have placed their bet (either match big blind amount or call any raises). Players use these 3 cards, plus the cards in their hand to make their best possible poker hand.
SoundPoker Says: The flop will usually determine if a player wishes to continue in the hand. Either with a hand they have already made, or hope to make on the turn or river.
See Also: Board, Community Cards, River, Turn
