A Three of a Kind is a hand with three cards of the same rank, and two other cards, each with different ranks. Three of a Kind hands are first ranked according to the rank of the card used in the three of a kind portion of the hand. The higher the rank of the card is in the three of a kind portion, the higher the hand is.
If two Three of a Kind hands share the card rank for the three of a kind portion of their hand, the two other cards in the hand are used to break ties. These two other cards are called kickers. The two kicker cards of each hand are sorted in terms of their ranks. Then the highest kicker card from each is compared, and if one hand has a higher kicker card than the other, that hand is ranked higher. If the first kicker is of the same rank, the comparison moves to the next kicker card and repeats.
The highest Three of a Kind hand is a Three of a Kind, Aces (with King kicker, Queen kicker). The lowest Three of a Kind hand is a Three of a Kind, Twos (with Four kicker, Three kicker).