What's a kicker in poker and how does it affect the outcome of a hand?

In Poker, a kicker is a card used to break ties between players with the same hand ranking. It is the highest card that doesn't contribute to the main hand. For example, if two players have a pair of Aces, the one with the higher kicker card wins. Kickers can greatly affect the outcome of a hand by determining the winning player when multiple players have the same hand.