In a Flush, the cards do not need to be consecutive in rank, but they must all belong to the same suit (hearts, diamonds, clubs, or spades). The ranking of a Flush depends on the highest card within the hand, meaning a Flush with a King is stronger than one with a Jack. If two players have a Flush, the one with the higher-ranking cards wins.
Flush Poker Example
For example, if you are dealt five cards: 2, 5, 9, Queen, and King, all of spades, you have a Flush, and its strength is determined by the highest card, the King.