The grid is the playing field of a Sudoku puzzle - 81 cells arranged in 9 rows, 9 columns, and 9 boxes. Every solving technique works on top of this fixed structure.
The grid is the Sudoku puzzle's playing field. The standard size is 9x9 - 81 cells arranged in 9 rows and 9 columns. Thicker borders divide it into nine 3x3 boxes. Every cell belongs to exactly one row, one column, and one box.
Each cell starts either as a given (a digit printed by the puzzle setter) or empty. Your job is to fill every empty cell so that all 27 houses contain the digits 1 through 9 exactly once.
Cells are addressed by row and column: R1C1 is the top-left cell, R9C9 is the bottom-right. Some books use letters for columns (A1 through I9), but the R{n}C{n} format is more common in modern strategy guides because it avoids confusion with letter-based variants like Wordoku.
Boxes are usually numbered 1-9 left-to-right, top-to-bottom: box 1 is the top-left 3x3, box 5 is the center, box 9 is the bottom-right.
Many Sudoku variants reshape the grid itself. 4x4 Sudoku uses a 16-cell grid for kids; 6x6 sits between mini and standard; 12x12 and 16x16 push the grid larger and use hex-style digit ranges.
Jigsaw Sudoku keeps 9x9 but replaces square boxes with irregular regions. Samurai Sudoku overlaps five 9x9 grids into a giant cross.
The standard grid is 9x9, but smaller and larger variants exist. 4x4 grids are common for children, 6x6 for warm-ups, and 12x12 / 16x16 for advanced challenges. The logic is the same; the digit range scales with the grid size.
Standard convention: thin lines between every cell, thicker lines outlining the nine 3x3 boxes. Givens are printed in bold; empty cells are blank. Most published puzzles also use 180-degree rotational symmetry of givens for visual balance.
The grid is the empty playing field; a puzzle is the grid plus a specific set of givens. Two puzzles can use the same grid with different givens and reach completely different solutions.
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