In the organized society of the villages, ninja are given missions depending on their rank. The missions are categorised in five ranks, based on how dangerous the mission is and how important it is. Any mission, regardless of rank, can involve being sent off to war, though.
These are light missions given to Genin fresh from the Academy. They are missions without the possibility of direct combat or danger to the shinobi's life. Examples are helping out on a farm or babysitting. A genin needs to have completed at least 8 D-rank missions to be able to participate in the Chunin Exams. The reward for a D-rank mission is between five thousand and fifty thousand Ryō.
These are missions given to more experienced Genin or Chūnin. They are missions anticipated to have some combat involved with the possibility of injury to the shinobi performing it. Examples are guarding people, background investigations, or capturing or suppressing wild animals. The reward for a C-rank mission is between thirty thousand and 100 thousand Ryō.
These are missions given to experienced Chūnin. They are missions anticipated to involve combat with other ninja. Examples are guarding people, espionage, or killing other ninja. The reward for a B-rank mission is between 150 thousand and 200 thousand Ryō.
These are missions given to Jōnin, concerning, among other things, village- or state-level matters and trends. Examples are guarding VIPs, or suppressing ninja forces. The reward for an A-rank mission is between eighty thousand and a million Ryō.
This is the highest rank of missions. They are given to experienced Jōnin and concern state-level confidential matters. Examples are assassinating VIPs, and transporting highly classified documents. The reward for an S-rank mission is more then a million Ryō.