Guide
How to play Tic Tac Toe
Everything below applies to the game on this site and to the version you scribble on paper at the back of a meeting.
The rules
- The board is a 3×3 grid of nine empty squares.
- One player is X, the other is O. X always moves first.
- Players alternate turns, placing one mark in any empty square. Marks are never moved or removed once placed.
- The first player to line up three of their own marks — horizontally, vertically or diagonally — wins immediately.
- If all nine squares fill and nobody has a line, the round is a draw. Some people call this a "cat's game".
Common questions
Is going first an advantage?
Yes, a real one. X gets five marks to O's four and sets the shape of the game. Against imperfect opponents, X wins far more often. That's why fair play alternates who starts — as the rematch system on this site does automatically.
How many winning lines are there?
Eight: three rows, three columns, and two diagonals. The centre square sits on four of them, each corner on three, and each edge on only two — a fact that drives most of the game's strategy.
Can a game have two winners?
No. The game ends the instant a line is completed, so a position where both players have three in a row can never legally occur.
What if we both play perfectly?
Every game ends in a draw. Tic Tac Toe is a solved game — with best play from both sides, neither can force a win. Winning is entirely about punishing mistakes, which is what makes the strategy worth learning.