What are the Texas Hold'em flush rules and how do they determine the winning hand in a game of poker?

In Texas Hold'em, a flush is a hand where all five cards are of the same suit. The winning hand is determined by the highest-ranking card in the flush. If two players have a flush, the player with the highest-ranking card wins. If the highest-ranking cards are the same, the next highest card is compared, and so on until a winner is determined.