Easy puzzles are great for getting started in sudoku, or as a warm-up for tougher stuff.
These puzzles can all be solved using crosshatching and single-candidate elimination.
To solve a moderate puzzles you'll need to go beyond basic crosshatching and look for pairs and the like.
To break a "hard" rated puzzle, you'll need to look for triples and number-claiming boxes.
In a really tough puzzle you're likely to find squares with lots of candidates,
and areas filled with seemingly unbreakable pairs and triples.
The answers are in there somewhere though - all these puzzles are guaranteed to be solvable by logic alone.
The wild bunch - these puzzles defied the basic solving logic in our puzzle generator.
That doesn't necessarily mean they can't be solved by logic alone - you might find that advanced techniques
such as X-Wing and Swordfish break them. Or you may have to take a guess.
Like all puzzles in the Gallery, outlaws have just one solution. Try them if you're tough enough!