If you're new to Sudoku, you've likely come across terms like naked pairs, hidden singles, or X-Wing in solving guides or forums. But what do these terms actually mean?
This post is your complete guide to Sudoku terminology, aimed at helping you understand essential strategy terms so you can elevate your puzzle-solving skills.
🧠 Why Learn Sudoku Strategy Terms?
Sudoku isn't just about filling numbers randomly—it's about pattern recognition and logic. Knowing the terms allows you to:
- Understand tutorials and strategy guides
- Communicate effectively with other Sudoku players
- Identify solving opportunities in real puzzles
Let’s break down the most important Sudoku terms explained for beginners and intermediates.
🔍 Hidden Single
Definition: A number that must go in a particular cell because it's the only place it can logically fit in a row, column, or 3x3 box—even if the cell has other candidates.
Example: In a row with empty cells, if only one cell can logically contain a 7, then that 7 is a hidden single.
✅ Use Case: One of the most basic and powerful Sudoku solving techniques.
👀 Naked Single
Definition: A cell that has only one possible candidate number remaining after elimination.
Difference from Hidden Single: In a naked single, the cell shows only one number. In a hidden single, the number is hidden among other options.
✅ Use Case: Ideal for quick early-game solves.
👯 Naked Pair
Definition: Two cells in the same row, column, or box that each contain the same two candidate numbers—and nothing else.
Why it works: Since these two numbers must occupy those two cells, they can be removed from the candidate lists of other cells in that unit.
✅ Use Case: Great for narrowing down options in tighter puzzles.
🕵️ Hidden Pair
Definition: Two numbers that appear as candidates in exactly two cells in a row, column, or box—even if those cells have other candidates.
Key Insight: You can eliminate all other candidates from those two cells.
✅ Use Case: A mid-game tactic to sharpen your board.
💡 Naked Triple / Hidden Triple
These are extensions of the above logic, involving three numbers across three cells.
- Naked Triple: Three cells that contain only three identical numbers in various combinations.
- Hidden Triple: Three numbers that appear only in three specific cells, potentially alongside other candidates.
✅ Use Case: Used in advanced puzzles with fewer clues.
❌ Pointing Pair / Pointing Triple
Definition: When a candidate number appears in only one row or column within a box, it cannot appear in that same row/column outside the box.
✅ Use Case: A strong technique for eliminating possibilities.
🧩 Box-Line Reduction (aka Box-Line Interaction)
Definition: A strategy similar to pointing pairs. If a number can only appear in one row or column of a box, eliminate it from that same row or column outside the box.
✅ Use Case: Helps reduce clutter in hard puzzles.
❗ X-Wing
Definition: An advanced technique that uses symmetry. If a number appears in exactly two rows and two columns, forming a rectangle pattern, you can eliminate that number from other positions in those columns/rows.
✅ Use Case: Highly effective in medium to difficult puzzles.
⚠️ Swordfish
Definition: A more complex version of the X-Wing involving three rows and three columns.
✅ Use Case: Rare but valuable in expert-level Sudoku.
🧠 Other Useful Terms
| Term | Definition | |------|-------------| | Candidate | A possible number that can be placed in a cell | | Pencil Marks | Small notes showing candidates in a cell | | Backtracking | A brute-force method of solving (not recommended) | | Guessing | Making assumptions without logical proof (avoid this!) | | Cell | A single square in the Sudoku grid | | Unit | Any row, column, or 3x3 box |
🔗 Want to Practice These?
Try our beginner-friendly puzzles: at our main game page
Or learn how to play step-by-step: How to Play Sudoku
📝 Conclusion
By understanding and applying these Sudoku strategy terms, you’ll not only boost your logical solving ability but also enjoy the game on a deeper level.
“Sudoku isn’t hard when you speak its language. Master the terms, and the solutions follow.”