Sudoku Source | Introduction to Sudoku

Contrary to what many people believe, Sudoku didn't actually originate in Japan. The game was first published in the U.S. in 1979 under the name of Number Place. Sudoku became popular in Japan in 1986 under the name of Sudoku, and it has just started to actually become popular in the U.S. in 2005 with the new Japanese name. Sudoku is the abbreviation of a Japanese phrase that means "the digits must remain single."

While some variations exist, a Sudoku puzzle is usually a 9×9 grid, made up of 3×3 subgrids, or "regions". Some cells already contain numbers. These numbers are known as "givens". As mentioned, the goal of Sudoku is to fill in the grid so that every row, every column, and every 3x3 box contains the digits 1 through 9. The numbers in Sudoku puzzles are only customary because no mathematics are involved with Sudoku, only logic. Any set of nine different symbols may be used in place of the digits 1 through 9, such as letters, shapes, or colors, but Sudoku puzzles rarely use such symbols.

Every Sudoku puzzle is designed so that there is only one solution. Obviously, it is against the rules to alter the "given" numbers, so it is necessary to work around those numbers. With any Sudoku-solving method or methods, you will learn that it is always incredibly easy to make a mistake. Once one mistake is made, a snowball effect of errors occurs, and you usually won't notice the mistake until so many mistakes have been made that you would either have to start over again of find a way to take out your frustration in some way. Visit the "If You're Frustrated" page for some guidance in these situations.

The guides, tips, and methods featured on this site come in three different sizes: Easy, Moderate, and Advanced. The easy methods are obviously easier and take less time to learn, but they are sometimes tedious and less effective. Consequently, the advanced methods are obviously more difficult and take longer to learn, but they are some quicker to use and more effective, if not necessary in some situations. The moderate methods are, well...moderate. The methods I will show may be applied at any point of solving a Sudoku puzzle when necessary. It's impossible for me to show you every situation that the various methods can be used in, so it is up to you to learn how to apply the various methods effectively.

If you're just starting to learn about Sudoku, I recommend that you read the Easy Tips & Guides pages. If those methods prove to be too easy or you master those techniques, feel free to move on to the Moderate Tips & Guides or Advanced Tips & Guides.