Land of Water

The Land of Water is one of the Five Great Shinobi Nations and contains the hidden village of Kirigakure. It is composed of many islands, with each having its own unique traditions. The Land of Water and Kirigakure are shown only briefly in the series, but several ninja featured in the series hail from this area.
Kirigakure ("Village Hidden in Mist") is the hidden village of the Land of Water. The leader of the village is known as the Mizukage. Madara Uchiha has been referred to as the Mizukage, though it is unclear when he held the title. The ninja in Kirigakure specialize in water-based jutsu. During the rule of the Fourth Mizukage, Yagura (who was also the host for the Three-tails), Kirigakure was known as "Bloody Mist" as it used brutal methods to train its ninja, requiring prospective ninja to fight their comrades to the death. The Fifth Mizukage was first seen when the Raikage called all Kages to the Land of Iron. After Zabuza Momochi killed all the students in his class, however, the process was discontinued. The Mist, like Iwagakure and Kumogakure, has also had possession of two tailed beasts, the three tailed beast and the six tailed beast. Zabuza became part of the Seven Shinobi Swordsmen of the Mist, the strongest group of ninja in the village and signified by the unique swords they carry. Aside from Zabuza, three other members have been revealed in the series: Kisame Hoshigaki, who abandoned the village and joined the criminal organization Akatsuki, Raiga Kurosuki, who is introduced towards the end of the Naruto anime, and a boy named Chojuro who is a bodyguard for the Mizukage. Suigetsu, who joined Sasuke when he killed Orochimaru, was trained to become a member of the seven swordsmen of mist. He has mention that his brother was/is a member of the swordsmen.

Land of Lightning

The Land of Lightning is one of the Five Great Shinobi Nations and contains the hidden village of Kumogakure. It is composed of numerous mountain ranges. The country and its inhabitants go largely unseen until late in the second half of the series.
Kumogakure ("Village Hidden in the Clouds") is the hidden village of the Land of Lightning. It is located on a high mountain, literally hidden in the clouds. The leader of the village is known as the Raikage. Similar to Iwagakure and Kirigakure, Kumogakure has had two tailed beasts in its possession: the two-tailed demon cat, sealed within Yugito Nii and the eight-tailed beast, sealed within the Raikage's younger brother, Killer Bee. Both Jinchūriki were attacked by Akatsuki. Yugito was captured and killed through the extraction process, while Killer Bee managed to fool and evade capture by his Akatsuki assailants. Back in times, a leader of the Kumogakure made an alliance with Konoha. After the celebration of the alliance, the leader tried to capture Hinata Hyuga, to get the Byakugan. Hinata's father killed the leader, but the rest of the Kumogakure saw that as a break of the alliance. They wanted the corpse of Hinata's father in exchange of their leader's life, or they would start a war between Kumogakure and Konohagakure. The Hyuga clan gave Kumogakure the corpse of Neji's father, instead for Hinata's father, because the Byakugan of Neji's father was sealed when he died, so the Kumogakure didn't get any Byakugan at last.

Land of Earth

The Land of Earth is one of the Five Great Shinobi Nations and contains the village of Iwagakure ("Village Hidden Among the Rocks"). The leader is called the Tsuchikage. Not much is known of this land as it has mainly been mentioned in passing in the manga. Like Kumogakure and Kirigakure, it has been revealed that Iwagakure had two tailed beasts in its possession: the four-tailed beast, sealed within an old man named Rōshi, and the five-tailed beast, sealed within a large, armor-clad man named Han.

Land of Waves

The Land of Waves is a poor nation, and as a result does not have a hidden village. It is an isolated island, but was prosperous until the country was taken over by Gato, who monopolized the economy. The Land of Waves is introduced early in Part I, and Team 7, which consists of the main characters of the series, travels to the Land of Waves as bodyguards for a bridge builder. With the aid of the populace of the Land of Waves, Team 7 manage to defeat Gato and his hired assassin Zabuza Momochi, and his assistant Haku, and restore the country to its former status. As a sign of gratitude, the bridge is named the "Great Naruto Bridge" in honor of Naruto Uzumaki, the main character of the series.

Tailed beasts

The tailed beasts are nine giant demons that serve to drive the plot of the Naruto series. They are differentiated by the number of tails they have, with each possessing an amount from one to nine. The beasts are large, living forms of chakra, giving them power that far outmatches most ninja. However, this immense strength is tempered due to their bestial nature, which restricts them from being smart enough to use it effectively. Beasts sealed within another person are able to benefit from the knowledge of their hosts, giving them the ability to speak and better utilize their powers. Akatsuki, a criminal organization that becomes one of the primary antagonists of the series, spends much of their screentime trying to capture the first nine beasts or their hosts. Once captured, Akatsuki's members seal the beast away for future use. The Akatsuki leader Pain, claims these beasts will facilitate in the creation of a weapon capable of destroying an entire country whilst the group's true leader Madara reveals his intention of merging the tailed beasts into their original form, the ten-tailed beast.
Only some of the beasts are actually seen in the series, and those that appear are not fully explained. The second Naruto artbook, released in July of 2009, provides an explanation of the beasts and their hosts. The beasts are, in numerical order: Shukaku, the one-tailed tanuki (sealed within Gaara of Sunagakure); the two-tailed monster cat (sealed within Yugito Ni'i of Kumogakure); the three-tailed turtle (previously sealed within Yagura of Kirigakure); the four-tailed gorilla, based on the Great Ape from Dragon Ball (sealed within Rōshi of Iwagakure); the five-tailed dolphin-horse (sealed within Han of Iwagakure); the six-tailed slug (sealed within Utakata of Kirigakure); the seven-tailed beetle (sealed within Fū of Takigakure); the eight-tailed ushi-oni-like beast (sealed within Killer Bee of Kumogakure); and the nine-tailed demon fox (sealed within Naruto Uzumaki of Konohagakure). As of the latest Naruto chapter, only the eight-tailed and the nine-tailed beasts have yet to be captured by Akatsuki.

Hosts

Jinchūriki ("Power of Human Sacrifice"?, English "Spiritualist Medium"), or simply hosts, are those who have had a tailed beast sealed into their bodies. Jinchūriki are created so that ninja villages can gain control over a tailed beast, having the host harness the beast's power as a weapon of battle. In most instances, they are actually stronger than the tailed beast they contain, as they have the knowledge to effectively control the tailed beast's strength. Each of the hosts that have appeared so far within the series also possess a physical characteristic that resembles their beast; Naruto for example has fox-like whisker-marks on his face, while Gaara has tanuki-like rings around his eyes.
According to members of Akatsuki, hosts of tailed beasts are typically lonely people who loathe humanity. When Akatsuki captured their first three jinchūriki, no one from their villages cared, and in fact were thankful to be rid of them. If a beast is removed from its host's body the host will die. Similarly if the host dies with the beast still sealed within them, the beasts will die too. Because of this beasts tend to be protective of their hosts, forcibly taking action when their host is in danger (as demonstrated with Gaara's sand shield). Hosts can communicate with their beast in an effort to use the beast's powers at will. Killer Bee (host of the eight tailed beast) seems to have had the most success in doing so, having a mutual relationship with his beast and being able to fully unleash the beast within him while still maintaining his sense of self. Naruto is the opposite; he is often in conflict with the fox and when he reaches four tails or more he loses complete control of his body.

Academy ninja

The academy is where would-be ninja start; they are not actually considered ninja until they graduate. Academy students take formal and practical tests of all sorts and are taught basic ninja skills, such as martial arts, techniques, physical fitness and the way of the ninja. Basic weapon usage, such as kunai and shuriken, are commonly taught. Elementary ninja techniques, such as transformation jutsu and clone jutsu, though they vary from village to village, are also taught. Once a student has become proficient in these areas they are allowed to graduate. Upon graduation, students are organized into three-man teams under the leadership of a Jonin. In some villages, the Jonin administers a final test to determine whether or not the team will be able to advance to the rank of Genin. Those who fail must return to the academy. When Naruto Uzumaki graduates at the start of the series, only nine of the twenty-seven graduates become Genin.