GENIN-The Genin is considered the lowest rank for a ninja. Most Genins don't perform missions, but train like academy students. Genin ranked ninjas usually perform harsh labor and dirty work. When put into missions, they usually perform D ranked missions. Every Genin is assigned a Jounin instructor. The Jounin instructor helps train the Genin to become a wise and skilled ninja
CHUUNIN-Chuunin rank is a medium ninja rank but hard to attain; the exams happen twice a year. A Genin team must be nominated by their Sensei and endure grueling written, physical, and mental exams to prove that he or she has what it takes to be a Chuunin. Ninjas have been killed during the Chuunin finals. When Naruto's team takes the Chuunin exam, only one person attains this title (Shikamaru). A Chuunin is considered a leader and is responsible for those under his command. Their mission parameters broaden and include higher-level missions ranging from simple escort or intelligence gathering to open combat and even assassination
JOUNIN-The title Jounin is split into two separate categories. Before you are awarded the full title Jounin, you are, by appointment, a Special Jounin. This is the next rank up from Chuunin and covers everything a Chuunin does, but also includes high-risk missions between other countries, such as: escorting royalty. These missions are much more delicate and dangerous than previous missions. Complete Jounins are assigned to the most dangerous and highest paying missions. These missions can be anything from high-level inter-nation assassinations to delivering and collecting important documents and treaties. Only a ninja with a wealth of combat experience can become a full Jounin. At some point in a Jounin's career he or she will be assigned a team of Genin to teach and guide their development. This responsibility is huge as they will oversee their students training and be responsible for their lives until they are Chuunin.
SANNIN-The Sannin is the name of three ninjas with with immense skill. Many times they are as powerful, if not more powerful, than Kages. They usually live away from the village to keep a low profile but are forced to keep in touch with the village every now and then for safety measures. Orochimaru, Jiraiya, and Tsunade are all considered to be the Sannin