Tic Tac Toe

Tic Tac Toe is game played on a three by three grid by two players. One player begins by marking either an O or an X in any space on the grid. The second player then must place the other mark upon a different grid coordinate. Play alternates until one player has achieved creating a row of three. The advantage indelibly goes to the player who goes first.

A more difficult version is played in three dimensions, usually with three grids laid side by side.

The game is also known as 'noughts and crosses', particularly in the UK, but the established and correct name is "Tic Tac Toe."