Sudopedia is a free online encyclopedia dedicated to the game of Sudoku.
If you are new to the game of Sudoku, you may want to read the introduction.
If you already know what Sudoku is, but don't know where to start, the main entry points are the indexes of terminology and solving techniques. Not every term is listed separately. The search facility can point you in the right direction.
If you like to contribute your knowledge to Sudopedia, you should visit the Community Portal where you will be guided to the areas that need expansion or improvement.
Registration is not required, but very useful for you and your fellow Sudopedians. Edits by unregistered visitors are marked with the visitor's IP address, which probably reveals more than a carefully chosen nickname.
All content is available under the GNU Free Documentation License.