Sudoku and logic puzzles

In short: Sudoku is a number puzzle on a 9×9 grid. Every row, column and 3×3 block must contain the digits 1 to 9 exactly once.

In more detail: A good sudoku has exactly one solution that can be found without guessing.

In detail

• Basic technique: Eliminate possible digits per cell (candidates).
• Naked single: If only one digit fits a cell, it is entered.
• Hidden single: A digit fits in only one place in a row, column or block.
• Advanced: Pairs, triples and X-wing.
• Similar puzzles: Kakuro, nonograms, logic puzzles with clues.
• Benefit: Trains logical thinking and concentration (lernen-lernen-methoden-die-wirklich-funktionieren).
• Programming: Sudoku can be solved with backtracking (spiele-ki-schach-go-und-poker).