Death Note (object)

The Death Note is a supernatural notebook which has the power to kill any human whose name is written into it. It is this premise which forms the central plotline in the series. Shinigami normally use Death Notes to kill humans from the Shinigami Realm, thereby adding each human's remaining years of life to their own. Rogue Shinigami are gods of death who drop extra Death Note(s) from the Shinigami Realm down to the human world in order to allow humans the use of their spare killer notebook(s). Historically, humans have either killed other humans with the Death Note(s) or ended up burning and therefore destroying the Death Note for any number of reasons. Ryuk is the first Rogue Shinigami that is shown in the manga, yet it is stated early in the series that there have been other Death Notes dropped in the human world before.

The Death Note is regarded to by Near as the most deadly weapon ever used in the history of mankind.

One of the eyecatch rules of the Shinigami Realm states that only 6 Death Notes can exist in the human realm at any one time. However, it is unknown how many killer notebooks exist in the Shinigami Realm, as well as how Death Notes are created (the King of Death, perhaps).

Light Yagami's Death Note
Light Yagami found this Death Note in the courtyard of his high school in Kyoto, Japan. It first belonged to Sidoh, but Ryuk stole it and dropped it into the human world because "he was bored." After testing the Death Note for the first time by killing a criminal, Light was clearly scared. However, after killing a second criminal whilst the man was attempting to commit rape, Light Yagami was mentally disturbed by the murders. It was at this point that he became the "entity" known as Kira, a name derived from the Japanese pronunciation of "Killer," given to him by the people of the country. Thus, Raito (Light) Yagami became the first human to use a Death Note with the intent to rid the entire planet of all evil in the name of Divine Justice.

Misa Amane's Death Note
Misa Amane's Death note was owned by Gelus, but Rem took it to the human world when the Shinigami died after saving Misa's life. It was then given to Misa by Rem.

Kyosuke Higuchi's Death Note
Kyosuke Higuchi's Death Note was previously Light's Death Note. Light gave ownership of this notebook back to Ryuk, who gave it to Rem, whom was instructed by Light to give it to a greedy human who would use it for his own gain. It was given to Kyosuke Higuchi by Rem.

Jack Neylon's Death Note (Mello's Death Note)
Jack Neylon's Death Note was previously owned by Sidoh, who traveled to the human world to retrieve it from Ryuk, who had given ownership to Light. One of Mello's henchmen traded the Death Note (which was, at the time, owned by Soichiro Yagami) for Sayu Yagami's life. It was given to Jack Neylon by Mello.

Differences between Death Notes
There are several different Death Note designs by Shinigami, including plain black (Rem's Death Note), English (Ryuk's 2nd Death Note, a.k.a. Sidoh's Death Note) and a Shinigami language (Gelus's Death Note, a.k.a. Rem's 2nd Death Note.) Other cover designs may exist as well, but that would be completely up to the Shinigami owning that particular Death Note. There are other Death Notes which are red or white as well, yet they are never shown in the manga or the anime. They are more rare than black Death Notes, however, they have the same effects as black Death Notes.