In poker, hands are ranked based on their strength, with the highest being a Royal Flush, which consists of A, K, Q, J, and 10 of the same suit. Following this is a Straight Flush, four of a kind, and a Full House. A Flush, Straight, and Three of a Kind come next, followed by Two Pair and One Pair. The lowest hand is a High Card, which occurs when no player has any of the above combinations. Understanding these rankings is crucial for strategic play and decision-making at the poker table.