SCORE: How to play

A Sudoku is a logic puzzle, there is no guessing involved, there is no maths involved, it is a pure logic puzzle.
This is an example of a starting grid for Sudoku - there is always some numbers that are given to you to start with. The more numbers you are given to start with, the easier the puzzle (normally).
There are three rules to Sudoku,
Each column must contain the numbers 1-9 once, and only once. The highlighted column already contains the numbers 5 and 7, you need to work out where the numbers 1, 2, 3, 4, 6, 8, and 9 need to go.
Each row must also contain the numbers 1-9 once, and only once. The highlighted row already contains the number 4, you need to work out where the numbers 1, 2, 3, 5, 6, 7, 8, and 9 need to go.
Each 3x3 region must contain the numbers 1-9 once, and only once. The highlighted 3x3 box already contains the numbers 2, 4, 6, and 7, you need to work out where the numbers 1, 3, 5, 8, and 9 need to go.
The easiest way to start is to look for cells where there is only one possible candidate. We know the bottom-left 3x3 region must contain the number 5 somewhere, but we don't know where. We also know that each row and column can only contain the number 5 once. This means we can eliminate all of the cells in that bottom-left square, apart from one. We can write in a '5' for the highlighted square.