• Sudoku is puzzle concerned with number placements
• Sudoku is played over a 9x9 grid, divided to 3x3 sub grids called "regions"
• The same single integer may not appear twice in the same 9x9 playing board row or Column or in any of the nine 3x3 sub regions of the 9x9 playing board
• The puzzle was popularized in 1986 by the Japanese puzzle company Nikoli, under The name Sudoku, meaning single number. It became an international hit in 2005

Rules and regulations:

• Sudoku is played over a 9x9 grid, divided to 3x3 sub grids called "regions
• Sudoku begins with some of the grid cells already filled with numbers

The object of Sudoku is to fill the other empty cells with numbers between 1 and 9 (1 number only in each cell) according the following guidelines:

1. Number can appear only once on each row
2. Number can appear only once on each column
3. Number can appear only once on each region

A summary of these guidelines would be, that a number should appear only once on each row, column and a region. 

Variants:-

The 9x9 grid with 3x3 regions is by far the most common, variations abound. But Sample puzzles can be 4x4 grids with 2x2 regions. 
5x5 grids with pentomino regions have been published under the name Logi-5; the World Puzzle Championship has featured a 6x6 grid with 2x3 regions and a 7x7 grid with six regions and a disjoint region.

Competitions:

Quite latest concept mainly includes world championship.
The puzzle was popularized in 1986 by the Japanese puzzle company Nikoli, under the name Sudoku, meaning single number. It became an international hit in 2005

Competitions

• The first World Sudoku Championship was held in Lucca, Italy, from March 10 to12, 2006.The competition included numerous variants.
• The second World Sudoku Championship was held in Prague from March 28 to April 1, 2007.
• The third World Sudoku Championship was held in Goa, India, from April 14 to16, 2008.
• The fourth World Sudoku Championship was held in Slovakia, from April 24 to 27, 2009.
• The fifth World Sudoku Championship was held in Philadelphia, USA from April 29 to May 2, 2010. 

Governing body:

Mission Statement In its capacity as a governing body, the World Sudoku Federation (WSF) is devoted to extending the role of Sudoku around the Globe.
It is therefore the Federation''s purpose to continue to teach and promote Sudoku, while encouraging and organizing tournaments.