Ranks

Genin

Genin are the lowest level of ninja and also the ones that display the most difference in power. When they become Genin, ninja start to do their bit for their village's economy – being sent on missions that the village gets paid for. They are typically sent either on D-rank missions, which are the lowest rank and are almost entirely risk-free jobs of manual labor, or, very rarely, on C-rank missions, which are a cut above that and begin to verge on real "ninja" work – though they generally have a very low possibility of risk to the ninja involved. Genin are put in four-man cells, consisting of three Genin and a Jonin sensei, in order to learn teamwork and experience true ninja life under the supervision and protection of an elite shinobi. The make-up of these teams is based on the individual skills of the Genin, so that there will remain a balance between the teams.

Chunin

Chunin are ninja who are qualified to watch over and guide other ninja. Chunin have reached a level of maturity that primarily consists of leadership skills and tactical prowess. Chunin are typically sent on C or B-rank missions. To become a Chunin, a Genin participates in a large examination with his or her team, known as the "Chunin Exams".

Jounin

Jounin are generally highly-experienced ninja with great individual skill who serve as military captains. They are often sent on A-rank missions, and experienced Jounin may even be sent on S-rank missions (which are considered to be the most difficult). They may also carry out these missions alone. They are sometimes assigned as sensei for three-person teams of Genin. Most Jounin are able to use at least two types of elemental jutsu.

ANBU

The ANBU is actually short for Ansatsu Senjutsu Tokushu Butai (Special Assassination and Tactical Squad). The name is a form of contraction, similar to English acronyms like SWAT, where the two kanji used to abbreviate the group's full name constitute an actual word on their own. The ANBU wear porcelain animal masks in order to distinguish themselves from normal shinobi and to conceal their identities. They also have standard uniforms consisting of black and gray armor, arm guards, and a signature spiral tattoo on their left shoulder. Certain ANBU wear black cowls over their standard uniforms, and squad leaders may wear white cowls.
Hunter Nin
Hunter nin are a special team within each Hidden Village given the specific duty of hunting down missing-nin. They kill their target, taking the head as proof, and then completely dispose of the body by using various methods, such as cremation or the summoning of wild carrion crows to devour the corpse. This is done in order to make sure the village secrets which a ninja's body holds -- such as chakra types, herbs eaten, ninjutsu, special medicine, and kekkei genkai -- will not be revealed to outsiders. Hunter-nin is also supposed to destroy the corpse at the very spot the body is lying; it is not to be moved after it is dead. As a requirement, they must possess a thorough and intimate knowledge of human anatomy. Due to their reputation for utterly and completely obliterating the remains of their targets, they are code-named "The Undertaker Squad." They are a branch of ANBU.

Kage

Those who have achieved the title of Kage are the leaders of the five most powerful Hidden Villages and generally the most powerful ninja in their respective villages. There may be exceptions, however; for example, a ninja may be the most powerful at the time of being installed as Kage, but may become less powerful upon aging, eventually being surpassed by a more youthful ninja. A Kage may retire and give the title to someone else; the title, once granted, is held permanently. This creates a case where there are two Kage at the same time, with only one of them actually active -- as was with the Fourth Hokage and the Third Hokage, where the latter had given up the title to the former, only to come out of retirement when the former died. The Kage stand equally with the rulers of their countries, oversee the activities of their villages, and are the leaders of ninja society.

Sannin

Sannin ninja have gained power far beyond a Jounin and earned a legendary status. This title is merely a class rather than an actual rank; the ninja's official rank with a village will usually still be Jounin, sometimes Kage. The allegiances of these ninja range from being part of the village's own ninja to being wandering ninja who are still loyal to their village. Sannin are usually the ones to take the Kage position if they settle down.