Sudoku Terminology: A Beginner-Friendly Guide to Common Sudoku Terms

If you have ever opened a strategy guide and felt lost at words like candidate, hidden single, or X-Wing, this Sudoku terminology guide is for you. The goal is simple: explain the most common Sudoku terms in plain English so you can follow tutorials, solve puzzles with more confidence, and learn new techniques faster.

For most beginners, only a small core vocabulary matters at first. Start with cell, row, column, box, given, candidate, naked single, and hidden single. Once those feel natural, the rest of the language becomes much easier to learn.

Quick Sudoku Glossary

Here are the fastest definitions for the Sudoku terms you will see most often:

• Cell: One square on the 9×9 grid.
• Row: A horizontal line of 9 cells.
• Column: A vertical line of 9 cells.
• Box: One 3×3 region. Some guides also call this a block.
• Given: A number that is already filled in when the puzzle starts.
• Candidate: A number that could still fit in a cell.
• Pencil marks: Small notes that track candidates inside a cell.
• Naked single: A cell with only one possible candidate left.
• Hidden single: A number that can go in only one cell within a row, column, or box.
• Elimination: Removing a candidate because Sudoku rules prove it cannot fit.
• Pair: Two cells linked by the same two candidates.
• X-Wing: An advanced pattern used to eliminate candidates across rows or columns.

Basic Sudoku Terms Every Beginner Should Know

Cell, Row, Column, and Box

These are the foundation terms in any Sudoku glossary. A standard puzzle has 81 cells arranged in 9 rows, 9 columns, and 9 boxes. The main rule of Sudoku is that each row, each column, and each box must contain the digits 1 through 9 exactly once.

If you understand these four words, you can already follow a basic explanation like: “The 7 cannot go in this cell because that row already contains a 7.”

Grid

The grid is the full Sudoku puzzle. Some articles say “board,” but grid is the more common term in Sudoku writing.

Given

A given is a number printed in the puzzle before you start solving. You cannot change givens. They are the fixed clues that make logical solving possible.

Empty Cell

An empty cell is simply a square you still need to solve. Beginners often scan rows, columns, and boxes to find empty cells with very few possible values.

Candidate Terms: Notes, Pencil Marks, and Elimination

Candidate

A candidate is any digit that still seems possible for a cell. If a cell cannot contain 1, 3, 5, 7, or 9 because of numbers already placed nearby, then 2, 4, 6, and 8 may be its remaining candidates.

Pencil Marks or Notes

Pencil marks, also called notes, are the small digits you write into a cell to track candidates. On paper, you write them lightly. In digital Sudoku apps, notes mode usually toggles them on and off automatically.

If you want a step-by-step walkthrough, see How to Use Notes in Sudoku.

Elimination

Elimination means removing a candidate because the rules prove it cannot fit. For example, if a row already contains an 8, then 8 can be eliminated from every other unsolved cell in that row.

Most Sudoku solving is really a chain of good eliminations. You remove impossible numbers until a move becomes obvious.

Common Solving Terms in Sudoku Strategy Guides

Scan or Scanning

Scanning means checking rows, columns, and boxes to see which digits are missing and where they can go. It is one of the first habits beginners should build because it helps you spot easy placements without guessing.

Naked Single

A naked single happens when one cell has only one candidate left. If only the digit 4 fits in a cell, then that cell must be 4. This is usually the first formal technique beginners learn.

Hidden Single

A hidden single is slightly different. A cell may still show several candidates, but only one of those digits can appear anywhere in that row, column, or box. That makes the placement forced even though it is “hidden” among other notes.

Guessing

In Sudoku discussions, guessing means placing a number without enough logical proof. Strong Sudoku teaching generally encourages solving without guessing, especially on beginner and intermediate puzzles.

For a broader overview of deduction-based play, see Sudoku Solving Strategies: Step-by-Step Guide for Every Skill Level.

Intermediate Sudoku Terms You Will See Next

Unit or House

Some advanced Sudoku resources use the word unit or house to mean any row, column, or box. If a guide says “this candidate appears twice in the house,” it is talking about one of those three structures.

Peer

A peer is any cell that shares a row, column, or box with another cell. If you place a 6 in one cell, every peer of that cell can eliminate 6 as a candidate.

Naked Pair

A naked pair happens when two cells in the same row, column, or box contain exactly the same two candidates, such as 2 and 9. Because those digits must go in those two cells, other cells in that unit can eliminate 2 and 9.

Hidden Pair

A hidden pair is the reverse idea. Two digits can appear only in the same two cells of a unit, even if those cells currently show extra notes. You can strip away the extra candidates and keep only the pair.

Locked Candidates

Locked candidates means a candidate is restricted to one line inside a box or one box inside a line. You will also hear the more specific names pointing and claiming.

Advanced Sudoku Terms You Will Hear in Expert Tutorials

X-Wing

An X-Wing is a pattern where the same candidate appears in two matching positions across two rows or two columns. When the pattern lines up correctly, you can eliminate that candidate from other cells in the affected columns or rows.

Swordfish

A Swordfish is a larger version of the X-Wing that works across three rows and three columns. It is less common in easy puzzles and more relevant once you move into harder grids.

Chain and Coloring

Chains and coloring are ways of following logical links between candidates. These methods are powerful, but most beginners do not need them right away. Learn singles, pairs, and locked candidates first.

How Sudoku Notation Works

Many strategy articles label cells with notation such as r4c7. This means row 4, column 7. Once you know this format, diagrams and walkthroughs become much easier to follow.

For example, if a guide says “place 3 in r4c7,” it means put a 3 in the cell where row 4 and column 7 intersect.

Which Sudoku Terms Matter Most First?

If you are new to the game, focus on these terms first:

1. Row
2. Column
3. Box
4. Given
5. Candidate
6. Pencil marks
7. Naked single
8. Hidden single

That small vocabulary is enough to understand most beginner lessons and solve many easy puzzles cleanly. After that, add pairs, locked candidates, and only then advanced patterns like X-Wing.

FAQ: Sudoku Terminology

What is the difference between a box and a block in Sudoku?

There is usually no difference. Most guides use box, while some use block for the same 3×3 region.

What are candidates in Sudoku?

Candidates are the numbers that can still legally fit in an unsolved cell based on the current state of the puzzle.

What does hidden single mean in Sudoku?

A hidden single means one digit can appear in only one cell inside a row, column, or box, even if that cell has other notes written in it.

Do I need to learn advanced Sudoku terms to solve easy puzzles?

No. Easy Sudoku puzzles are usually solved with scanning, eliminations, naked singles, and hidden singles. Advanced terms matter later.

Where should I practice after learning Sudoku terms?

A good next step is to solve a fresh puzzle and apply the terms in real time. Try a daily Sudoku puzzle and name each move as you make it.

Conclusion

Learning Sudoku terminology makes every tutorial easier to understand. Once words like candidate, hidden single, and locked candidates stop feeling abstract, you can read strategy guides faster and make better decisions on the grid.

If you want to keep building from here, start with notes and singles, then move into a full strategy guide, and finally practice on a fresh daily puzzle. The more often you connect the terms to real moves, the faster they stick.