Tic-tac-toe (American English), noughts and crosses (Commonwealth English), or Xs and Os (Canadian or Irish English) is a paper-and-pencil game for two players who take turns marking the spaces in a three-by-three grid with X or O.
The player who succeeds in placing three of their marks in a horizontal, vertical, or diagonal row is the winner. It is a solved game, with a forced draw assuming best play from both players.
"Nought" is an older name for the number zero, while "cross" refers to the X shape.
The game has various English names, including:
Tick-tack-toe, tic-tac-toe, tick-tat-toe, or tit-tat-toe (United States, Canada).
Noughts and crosses or naughts and crosses (United Kingdom, Republic of Ireland, Australia, New Zealand, South Africa, Zimbabwe, India).
Sometimes, tic-tac-toe (where players keep adding "pieces") and three men's morris (where pieces start to move after a certain number have been placed) are confused with each other.