A standard 9×9 Sudoku grid must be filled such that every row, every column, and each of the nine 3×3 subgrids contains all digits from 1 to 9 without repetition.

Basic strategies include Naked Singles (a cell with only one candidate remaining) and Hidden Singles (a candidate that can only appear in one cell of a unit). Advanced techniques include Naked Pairs/Triples, Pointing Pairs, and X-Wing elimination.

Sudoku exercises focused attention, working memory, deductive logic, and numerical pattern recognition through step-by-step problem solving.