A payline in slot games is a line that determines how a combination of symbols results in a win. It is the path that a winning combination must follow on the reels. Paylines can be straight, diagonal, zig-zag, or any other pattern depending on the game. Understanding paylines is crucial for players to know how winning combinations are formed. The number of paylines varies from game to game, affecting the chances of winning. Players can usually adjust the number of active paylines to customize their gameplay experience.