Sudoku is a logic-based number placement puzzle that has gained worldwide popularity. The objective is to fill a 9×9 grid with digits so that each column, each row, and each of the nine 3×3 subgrids contains all of the digits from 1 to 9 without repetition. The puzzle setter provides a partially completed grid, and the challenge lies in figuring out the remaining numbers. Sudoku requires no mathematical calculation but relies on logical reasoning and pattern recognition. The game originated in Switzerland and gained international popularity after being published in Japan, where it got its name (数独, sūdoku, meaning 'single digit').