How is sudoku played?

The point of sudoku is to write in numbers one through nine so that they fill in all of the boxes. However, the premise of the puzzle may seem easy, but it is actually difficult to do. The sudoku puzzle includes a grid with eighty-one boxes. The boxes are arranged in a nine by nine grid so that there are nine rows of boxes followed by nine columns of boxes.

There are already numbers filled in about 1/3 of the boxes are filled in with the others empty. It is up to the puzzler to write in different numbers from one through nine, so that each row has numbers 1-9 without repeating any numbers in it. Then each column has numbers 1-9 in it without repeating. Plus, each three by three grid has one through nine in it.