Strategy

Tic Tac Toe

Get three in a row

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About Tic Tac Toe

Tic-tac-toe is played on a three-by-three grid, with players alternating X and O and aiming for three in a row horizontally, vertically, or diagonally.

It is also completely solved: with correct play from both sides, every game is a draw. That makes it less a contest than an exercise in not making the one mistake that loses.

How to play

  1. 1Take turns placing your mark in any empty square.
  2. 2Win by completing a line of three, in any row, column, or diagonal.
  3. 3Block your opponent whenever they have two in a row with the third square open.
  4. 4If the grid fills with no line of three, the game is drawn.

How to never lose

  • Take the centre if it is free. It belongs to four of the eight possible winning lines, more than any other square.
  • If the centre is taken, take a corner. Corners appear in three lines each, whereas edge squares appear in only two.
  • Always check for your own winning move first, then for your opponent's, in that order.
  • Play for a fork: a single move that creates two threats at once cannot be blocked and wins.
  • Against an opponent who opens in a corner, replying in the centre is the only move that reliably holds the draw.

Frequently asked questions

Is there a way to always win at tic-tac-toe?

No. Against an opponent playing correctly, every game ends in a draw. You can only win if your opponent makes a mistake, so the practical skill is never making one yourself.

What is the best first move?

The centre, which belongs to four of the eight winning lines. Corners are the next best, and edges are the weakest opening squares.

What is a fork in tic-tac-toe?

A move that creates two separate threats to complete a line at once. Since your opponent can only block one of them, a successful fork wins the game.