Genin
Genin Literally meaning: low ninja, Meaning: junior ninja) 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.
They are sent on a D-rank missions, the lowest rank which are almost risk-free missions, or more experienced Genin are sent on a C-rank missions, which begin to do a real "ninja" jobs with their sensei often guides them on a missions. Ever since Konoha got attack by Otogakure and Sunagakure, they have been forced to send their Genin on top-ranked missions, especially without any Jounin to watch over them.
Chuunin
Chuunin are the ninja who are qualified to leader their squad in their variety of missions. To become a Chuunin. You must be Genin to participates in a exam called “Chuunin Exams” with a team. And you don't need to win because they don't look for winners they want to see who has the best performance, for example when Shikamaru forfeit his match instead of winning he still became Chuunin. But it doesn’t need to be with your own team like Sakura Haruno who became a Chuunin with different team because Naruto and Sasuke wasn't around that time because Shikamaru is already Chuunin in his team so Sakura was in Choji and Ino team for this exam during time-skip.
After the ninja becomes Chuunin level, they can wear shinobi tactical vest that holds any ninjutsu scrolls and ninja weapons that would come in handy during missions. They look for more elaborate clothing like capes or robes.
Jounin
Jounin are the one who known for their highly-experience ninja with great skills that serve as a military captain. They are mainly sent on a A-rank missions and they may also be sent on a S-rank missions which is a really difficult. They sometime carry out missions alone. They also sometime assigned as sensei for three-person teams of Genin.
Kakashi became a Jounin at age of 13 this suggest that he is youngest Jounin
It is mention that the most of the Jounin can use at least two chakra natures it is known as elemental jutsu. It is mentioned Naruto databook which is canon.
There are some Special Jounin who are slightly above normal Jounin and they have special ability. They are elite specialists in their areas and they often get assigned as subordinates to regular Jounin when their services are needed. For example Yamato became a team captain of team 7 when Kakashi was in hospital because he over used his Mangekyou Sharingan.
Kage
Those who have achieve the Kage rank are leader of the village and that make them the most powerful ninja in their village. There are five Kages who lead their villages like Hokage leader of the Hidden Leaf Village, Kazekage leader of the Hidden Sand Village, Raikage leader of the Hidden Cloud village, Tsuchikage leader of the Hidden Stone Village and Mizukage leader of the Hidden Mist Village. Sometime a Kage may retire and give the title to someone else like third Hokage retired and Minato became fourth Hokage. Once the title is granted, it is permanent. Some Kage do have family members who were previous Kage or sometime a student can be personally taught by a former Kage like Gaara who succeeded his father as a Kazekage or fourth Hokage was trained by the third Hokage student jiraiya.
