Shinobi are the primary focus and the main military power in the series. A female ninja is known as a kunoichi. Most come from a hidden village, of which some come from specialized ninja clans, and will perform missions for a fee. These missions can include: doing manual labor, acting as escorts, gathering secret information, retrieving stolen items, carrying out assassinations, etc. In times of war, ninja will come together to defend their villages and land. The clearest characteristic of a shinobi is their ability to manipulate chakra to create and use techniques. Shinobi are expected to be loyal to their villages for life, and any defectors are considered to be missing-nin, and will be marked for death.
Ninja tools are used as alternatives to techniques. They can include weapons, accessories, and even clothing. Some ninja such as Tenten have mastered the use of such tools, but all ninja are able to use the most common to some degree. A standard shinobi will have a pouch equipped with many tools, and nearly every ninja is equipped with at least a shuriken holster. Most also possess and wear a forehead protector with the symbol of the village they derive from, though the ninja does not necessarily have to wear it over their forehead. The Inuzuka clan's ninken and Aburame clan's insects are also classified as tools.
- The word "shinobi" and "endure" both have the same kanji character.