Jacky Liao and Tony Liao describe the main attributes of Sudoku and provide tips on how to solve the puzzle. Sudoku is a popular puzzle just like crossword. It is a puzzle of a 9X9 square sub-divided into 3X3 squares. You have to fill each column and row with digits 1 through 9 in any order. Each 3X3 sub-square must include all digits 1 through 9. Every Sudoku game starts with a few of the squares filled in. The more squares that are filled in the easier it is to play. As you fill in the squares correctly, your options are reduced and it becomes easier to fill in the remaining squares. Don't panic when you reach squares where you are not sure what to fill in to them. Mark the possibilities in small digits and when one of them is correctly filled, fill the other without worry.