Tic Tac Toe

A game in which two players alternately put crosses and circles in one of the compartments of a square grid of nine spaces; the object is to get a row of three crosses or three circles before the opponent does
If you know what you are doing, you can't lose at Tic-Tac-Toe. If your opponent knows what they are doing, you can't win at Tic-Tac-Toe. The game is a zero sum game. If both players are playing with an optimal strategy, every game will end in a tie.Surpisingly few people know optimal Tic-Tac-Toe stategy. Yes there are some people (and computers) that you will never beat, but they are relatively rare. Knowing this, you can become a Tic-Tac-Toe master.
Neither of the computer players can be beaten because they are playing as well as game can be played. The computer does this by playing out every single game of Tic-Tac-Toe ahead of time and figuring out which moves are good and which are bad. The computer can do this because there are not a lot of possible games. The first move can be played in any of nine squares, the second in any of eight squares, the third in any of seven squares and so on. That means there are at most nine factorial or 362,880 possible games. A computer can breeze though 400,000 games in a blink of an eye. In reality, it has to play far fewer games than that. There are only 125,168 games of Tic-Tac-Toe because somebody wins most of them before all off the squares have been filled. The Tic-Tac-Toe is symetrical and if the computer can realize that many games are the same because it could rotate the board, there are even fewer games than that. Suffice to say that computers win through brute force.
So how can a human become unbeatable in Tic-Tac-Toe? A human doesn't even have time to play out one hundred games in the mind and still make a move in a reasonable amount of time. However, a human can compensate with experience and reasoning.