Rules of the Death Note

The Rules of the Death Note are the official rules that govern how the Death Notes work.

Ryuk writes five of the rules down into his second Death Note before dropping it into the human world so that whichever human picks it up will know the basics of how to use it. Additional rules are revealed throughout the series.

For a full list of the original rules, see Rules of the Death Note/Manga Chapter Rules.

Manga chapter rules
These are the full-page rules provided at the end of manga chapters titled "How to Use It", and they are the main rules of the series. The rules are essentially identical in the anime, and are the original rules on which the other adaptations are based.

The first five rules are the ones Ryuk wrote in the Death Note, and which are provided with the first "How to Use It" page:

A total of 70 pages (68 in Viz's edition) were released. The Japanese mis-numbered two of their rules, reusing the numbers again; Viz instead removed two pages so that the numbers wouldn't be duplicated. Viz also renumbered some of these rules. This issue is only in rules released in volume 7.

How To Read rules
The original manga rules were reorganized by subject in the manga guidebook Death Note 13: How to Read. They are essentially the same as the original manga rules.

For a full list of these rules, see Rules of the Death Note/How to Read Rules.

Fake rules
In the series, Light Yagami convinces Ryuk to write down fake rules to mislead investigators and clear himself and Misa Amane of suspicion.

These are the fake rules that Ryuk writes in the Death Note:
 * If the user of the Death Note fails to consecutively write names within 13 days of each other, then the user will die.
 * If a person makes this notebook unusable by tearing it up or burning it, all the humans who have touched the Death Note will die.

In other media
With the exception of Netflix's 2017 film, the adaptations mostly honor the original canon rules.

Pilot chapter
In the manga pilot chapter, there is nothing written in the notebook when Taro Kagami first picks it up. The rules are later explained by Ryuk.

Some of the rules are different than what's later used in the manga. For instance, Ryuk says in the pilot chapter that "the notebook has 60 pages with 38 lines per page," and that when the owner runs out of space to write in the notebook, they "may ask the original Shinigami owner for another." In the manga canon rules (How to Use It: XXXI), it's stated that "the number of pages of the Death Note will never run out."

Rules provided in the pilot chapter:
 * The notebook has 60 pages with 38 lines per page. If you write small, you can cram in as many names as you want.
 * The Shinigami's voice and form will go completely unnoticed by others.
 * In return for letting you keep the notebook, the Shinigami may take it back at any time.
 * Those who do not wish to be followed by the Shinigami can get rid of him simply by giving the notebook back or throwing it away.
 * It is up to the owner to decide how to use the notebook -- whether it be for world conquest, getting rid of that one guy, or choosing to not keep such a terrifying item.
 * This Death Note can only be used by the one who found it. If the owner throws it away or loses it, the right of ownership is automatically transferred to whoever next picks it up.
 * One must know the face of the person whose name is written down for there to be an effect. That way, people with the same names will not be affected all at once.
 * If you write a cause of death after the name like this: (Name) died from (cause), then that will happen.
 * You can write with any pen: the color doesn't matter. If you use a sticker with a name printed on it, there will be no effect. Please write directly onto the notebook. It would be a good idea to change your handwriting as much as possible.
 * These letters cannot be erased. (Arrow pointed at the words "Death Note" on the cover.)
 * If the cover is destroyed, the notebook cannot be used.
 * Be careful not to let other people see it.
 * You will not die if you write your name here, but it is not recommended. (Arrow pointed at the cover.)
 * When you run out of room to write in the notebook, you may ask the original Shinigami owner for another. How many Death Notes would you need?

The pilot chapter also includes the Death Eraser, which can undo deaths. Ryuk explains:
 * "If you erase a name in the notebook with this, that person will come back to life -- so long as he hasn't been cremated yet."

Japanese film series
In the opening sequence for Death Note: The Last Name, the second rule in How to Use I is shortened to "This note will not affect people sharing the same name."

Netflix 2017 film
Some major changes to the rules were made for Netflix's 2017 Death Note film. Most notably: the default cause of death is a random accident (instead of a heart attack), a victim can only be controlled for 2 days (instead of 23 days), and a person whose name is written in the notebook can be spared if the page is destroyed before their death.

Most rules in the Death Note used in the film are rephrased versions of the original rules. Several of the rules still reference heart attacks as the default cause of death, although this was changed in the storyline, so the rules seen written in the film are not necessarily applicable.