Invented by an American named Howard Garns and originally called "Number Place", the game we today know as Sudoku became very popular in Japan during the 1980s, where it was renamed "Su Doku." Sudoku puzzle books are hugely popular today because the game is easy to learn and Sudoku puzzles are available at various levels of difficulty, ranging from easy Sudoku to hard Sudoku. Often described as brain puzzles, mind puzzles or logic puzzles, Sudoku is a game of logic in which you need to use deductive reasoning and search for patterns in order to place missing numbers on a grid. It is also a game that can be played anywhere, and so it is ideal for moments of down-time during the day or, for example, for combating the boredom of commuting. Suitable for all ages, Sudoku is a brain game which can help us to continue learning and stay mentally healthy throughout our lives. Indeed, recent studies show that playing Sudoku may well play an important role in helping people to reduce the risk of dementia as they get older. Sudoku is not a mathematical game and indeed requires no knowledge of maths. Numbers are used simply because they are universally recognized symbols. The game could however be played using different colors, pictures or letters of the alphabet. Indeed, variations of the game, using a larger grid than the most commonly used 9 x 9 grid, often use either a combination of numbers and letters, or simply letters. If you have not yet learned how to play Sudoku then you will discover that it is a great way to escape, relax, keep your mind active while, most important of all, having Fun!