These are some types of missions that a typical Ninja would complete in their daily routine.
S-Rank missions are the highest-paid missions a ninja can complete. They are extremely dangerous and are usually only assigned to a few highly skilled ninjas.
Jounin rank ninjas complete these missions and usually include important tasks that will greatly benefit the hidden village or country, such as assassinations of wanted criminals and escorting important people across dangerous territory.
B-Rank missions are mostly completed by Chuunin rank ninjas. They usually involve assignments such as reconnaissance missions and assassinations of low-ranking enemy ninjas.
These are completed mostly by Chuunins but are sometimes done by Genins as well. Various assignments include hunting wild animals for food and acting as a bodyguard for important villagers.
This is the lowest class mission that can be completed and is usually done by Genins. These missions are usually a small priority and involve completing small errands for people around the village.