Some people are confusion ranks and classifications so I'm going to post them and give an explanation.
E-Rank: The lowest level in the ranks, it means that you are an inexperienced fighter with almost no abilities ((Noob muhahaha)) Academy students are in this rank.
D-Rank: Means you are just starting to get some experience and your starting to learn new abilities. Gennin are of this level.
C-Rank: The experienced level, at this level you have quite an amount of experince, you have quite a few jutsu at in your arsenal, and this is around the time Keke Genkai are mastered. Chuunin get this level.
B-Rank: This is an elite level, This is recognised as an advanced level. In this category the shinobi is a specialist in a certain field. Jounin, ANBU, medical nin, and Hunter nin fall in this category.
A-Rank: This is the rank that many aim for, but dont achieve, this is the Sannin and Kage level, as for as experience and skill go, they are unmatched.
S-Rank: This rank means you are of legendary statis. This rank means you are known throughout every country as exceptionally talented.
The majority of kages, Jiraiya, Orochimaru, and akatsuki hold this rank.
In addition to the status of the fighter, these ranks also work for jutsu. An example would be the Kage Bushin no jutsu ((shadow clone)) It is a B-ranked jutsu, meaning it's jounin level.
