Tic-tac-toe is a paper-and-pencil game for two players, X and O, who take turns marking the spaces in a 3×3 grid. The player who succeeds in placing three respective marks in a horizontal, vertical, or diagonal row wins the game. This is also known as "tic toc toe", " Dots n lines " "X and O" CROSS and ZEROs, O-X, Noughts and crosses or Naughts and crosses. Etc.