Sudoku rules explained in plain language
Sudoku looks complex at first, but the core rule is simple. Every row, every column, and every 3x3 box must contain the digits 1 through 9 exactly once. Everything else is logic built on that foundation.
Core SudokuX pages
These links connect the content pages to the core product pages, which helps both users and crawlers move through the site naturally.
Rows and columns
Each row and each column must contain all digits from 1 to 9 without repetition. If a number is already present in a line, it cannot appear there again.
The 3x3 box rule
Each 3x3 box follows the same no-duplicates rule. A valid move must satisfy the row, the column, and the box at the same time.
What counts as solved
A Sudoku board is only solved when the entire grid is filled and every row, column, and box satisfies the rule together. A full board can still be wrong if even one placement breaks that structure.
Related Sudoku pages
Keep practicing with live boards
Helpful content should lead naturally into the product. If you want to practice what you just read, open a standard board, try the daily puzzle, or compare your progress on the leaderboard.