In the game of checkers, a regular piece is promoted to a king once it reaches the opponent's back row on the opposite side of the board. This promotion occurs automatically when the piece lands on a square in the last row of the opponent's side. Upon reaching this square, the regular piece is transformed into a king, which is typically represented by stacking another piece on top of it. A king has greater movement capabilities compared to a regular piece, as it can move both forward and backward diagonally. This change in status enhances the player's strategic options during the game, allowing for more complex plays and positioning. If you have any further questions about the game or its rules, feel free to ask.