Sudoku

What is Sudoku?
Sudoku is a number-placement puzzle. You start with an almost empty puzzle, which has some of the cells already filled with numbers. Your objective is to fill in the rest of the empty cells. According to the Sudoku rules, a number can appear only once in every row, column, or region (3X3).

How do I start a Sudoku puzzle?
The easiest way to begin is to choose a number and try to fill in all the places in the puzzle where it must appear, according to the Sudoku rules. When you finish dealing with the first number, choose another number. Repeat these steps for all the numbers from 1 through 9. As the puzzle starts to fill, you will find new places to fit the earlier numbers, so you may go back to those other numbers and place them in the grid. At the end there will be no empty boxes left, and the puzzle will be complete.