Tic-tac-toe is played on a three-by-three grid by two players, who alternately place the marks X and O in one of the nine spaces in the grid. Players soon discover that the best play from both parties leads to a draw. Tic-tac-toe is often played by young children who may not have discovered the optimal strategy. Games played on three-in-a-row boards can be traced back to ancient Egypt, An early variation of tic-tac-toe was played in the Roman Empire, around the first century BC where such game boards have been found on roofing tiles dating from around 1300 BC.