Line Three: look for threats before opportunities.
A practical order for reading a tic-tac-toe board: win, block, then investigate forks.
There are only nine squares, but choosing a promising-looking one is not enough. A move can build a future threat while ignoring an immediate loss. A dependable way to read the board is to check urgent outcomes first and positional opportunities second.
First, take a win that already exists
Scan the three rows, three columns, and two diagonals. If any line contains two of your X marks and one empty square, filling that square wins. You do not need to block an opponent’s threat if your own move ends the game first.
X X · O O · · · ·
In this position, X should play the top-right square. Blocking O at the middle-right square would miss an immediate win. A checklist that says “always block” is incomplete; winning this turn comes first.
Second, prevent an immediate loss
If you have no winning move, find any line with two O marks and an empty square. Occupy that empty square. For example, when O has both upper corners and the top-middle square is empty, the middle square is urgent regardless of how attractive the center may seem.
If O has two distinct winning squares, one blocking move may not be enough. That usually means an earlier move allowed a fork. Reviewing the previous turn helps you find the cause rather than blaming the final forced position.
Third, understand a fork precisely
A fork is a move that creates two separate ways to win on the following turn. Here is a position with X to move. Consider the lower-left square.
Before X moves: After X takes lower-left: X · · X · · · O · · O · · O X X O X
The new X creates a threat in the left column: middle-left would complete three X marks. It also creates a diagonal threat from lower-left to upper-right, but the center is occupied by O, so that diagonal is blocked. The bottom row is blocked by O as well. This move creates only one immediate threat. It is not a fork.
Counting open lines explicitly is better than remembering a vague slogan such as “opposite corners always create a fork.” The exact occupancy matters.
A genuine two-threat example
X O · · · O X · ·
X can win immediately by taking middle-left, so that is the best move. But as an exercise in recognizing structure, placing X at lower-right would create threats at lower-middle and center. Both winning lines would be open. This demonstrates a fork while also showing why the earlier priority—take an immediate win—still comes first.
What to expect from our opponent
The computer searches legal continuations and avoids losing when it can. With careful play from both sides, draws are expected. Use each round to practice checking every line and identifying the reason for a move. You do not have to beat the computer for the exercise to be useful; a well-defended draw means you prevented its threats.