This is a glossary of Sudoku terms and jargon. It is organized thematically, with links to references and example usage provided as ([1]). Sudoku with a 9×9 grid is assumed, unless otherwise noted. Terminology and grid layout A Sudoku (i.e. the puzzle) is a partially completed grid. A grid has 9 rows, 9 columns and 9 boxes, each having 9 cells (81 total). Boxes can also be called blocks or regions. Three horizontally adjacent blocks are a band, and three vertically adjacent blocks are a stack. The initially defined values are clues or givens. An ordinary Sudoku (i.e. a proper Sudoku) has one solution. Rows, columns and regions can be collectively referred to as groups, of which the grid has 27. The One Rule encapsulates the three prime rules, i.e. each digit (or number) can occur only once in each row, column, and box; and can be compactly stated as: "Each digit appears once in each group." Other terminology Automorphic – A property of some Sudokus where the digits (not just their positions) play a role in a type of symmetry. Backtracking – A programming method to solve Sudokus, but can also describe a manual method. In the manual form, it indicates the effort of making a guess, and if found to be wrong, going back (i.e. backtracking) and making a different guess. In solving most Sudokus, this is usually a poor approach, but in the most difficult examples may be necessary. Constraints – The rules of a Sudoku that require each digit to appear only once in each row, column, and box. Element – A digit or number of the Sudoku. This term is often used in a mathematical context, especially for Sudokus larger than 9×9, when more than nine digits "1-9" are required. In large Sudokus, such as "Sudoku the Giant", elements may be alphanumeric, or a larger set of numbers, e.g. "1-25". Latin square – A related puzzle, or number array, with only row and column constraints (omitting the box constraint). Minimal – A minimal Sudoku (or irreducible Sudoku) is a Sudoku from which no clue can be removed leaving it a proper Sudoku (has one solution). Different minimal Sudokus can have a different number of clues. Minimum number of clues – Refers to the minimum of all proper Sudokus. (See Mathematics of Sudoku – Minimum number of givens for details). Nonet – Another term for the