The term Sudoku implies "numbers singly", or loosely translates to "all the numbers must remain unmarried", in Japanese; it is a registered trademark of puzzle publisher Nikoli Co. Ltd in Japan. Other Japanese publishers generally refer to the puzzle as Nanpure (Number Place), its original title. Sudoku is pronounced as the English words "SUE-dough-coo", with the first syllable accented.
Rules and terminology
The puzzle is most frequently a 9×9 grid, made up of 3×3 subgrids called "regions" (other terms include "boxes", "blocks", and the like when referring to the standard variation). Some cells already contain numbers, known as "givens" (or sometimes as "clues"). The goal is to fill in the empty cells, one number in each, so that each column, row, and region contains the numbers 1–9 exactly once. Each number in the solution therefore occurs only once in each of three "directions", hence the "single numbers" implied by the puzzle's name.