Popular logic puzzle is a term used to describe a type of puzzle that requires logical thinking and problem solving skills. The most popular type of logic puzzle is Sudoku, which is a number-placement puzzle consisting of a 9x9 grid with several given numbers. The objective is to fill the empty cells with numbers from 1 to 9 in such a way that each row, column, and 3x3 sub-grid contains all of the digits from 1 to 9.