It beats all other hands, but you don't see it very often. If two players have them, the hand with the higher cards in the Three of a Kind will break the tie. In a tie, the hand with the highest card wins. Some poker games allow other card rankings, too. In some games, one pair can rank if the pair is above a Ten or a Jack, while other games will allow any pair to rank.
Some games also allow a high card to rank in a case where no other hand is played to beat it.
In Blackjack, players play against the dealer, betting that the value of their hand will beat the value of the dealer's hand, without going over a score of 21. If the first two cards dealt total 21, it is called a Blackjack or natural, and the player will win against the dealer. If the first two cards dealt are a pair, the player can choose to split them. This turns one hand into two, but it also turns one bet into two. The player plays both hands, but must bet separately on each one.