and each of the nine 3×3 subgrids that compose the grid (also called "boxes", "blocks", or "regions") contain all of the digits from 1 to 9. The difficulty level of a Sudoku puzzle can be easy ...

Sudoku is a logic-based number puzzle played on a 9x9 grid. The objective is to fill in the grid so that each row, column, and 3x3 box contains the numbers 1 to 9, without repeating any numbers.