Sudoku involves a grid of 81 squares. The grid is divided into nine blocks and each block contains nine squares. Each of the nine blocks has to contain numbers between 1-9. every number in a block should be unique. Each number can only appear once in a row and a column.
To play Sudoku on this site click the generate button. This will create a game of Sudoku with only one solution. If you want to see what the solution is you can click the solve button.