That's what most people think. The game is played on a grid that's 3 squares by 3 squares.
Players take turns putting their marks in empty squares.
When all 9 squares are full, the game is over. If no player has 3 marks in a row, the game ends in a tie. Strategy means figuring out what you need to do to win. Part of your strategy is trying to figure out how to get three X s in a row. The other part is trying to figure out how to stop the computer from getting three O s in a row.