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. There is no universally agreed rule as to who plays first, but in this article the convention that X plays first is used.

When you're the first one up, there is a simple strategy on how to win tic tac toe: put your 'X' in any corner. This move will pretty much send you to the winner's circle every time, so long as your opponent doesn't put their first 'O' in the center box. This can make it harder to win, but it can happen.