Reversi is a two-player board game played on an 8x8 grid. Each player takes turns placing their colored discs on the board, with one player using black discs and the other using white. The objective is to capture the opponent's discs by surrounding them, flipping them to your color. The game ends when the board is full or no more moves can be made. Players can only place a disc in a position that outflanks one or more of the opponent's discs. The player with the most discs of their color on the board at the end of the game wins. Reversi is known for its simple rules but strategic depth.