Kage (Naruto)

A Kage (影; Literally meaning "Shadow") is the leader of one of the five most powerful hidden villages and are generally acknowledged as the most powerful ninja in their respective villages. They are collectively known as the Five Kage (五影, Gokage; Literally meaning "Five Shadows").

The Five Kage.

If a Kage feels like they are incapable of leading their hidden village to its fullest, the Kage may retire and give the title to someone else. The title, once granted, is held permanently, that means even after they demit office they are still referred to as "Kage". This creates a case where there are two Kage at the same time, with only one of them actually being active, as it was with the Third and Fourth Hokage. After the Fourth died, the Third came out of retirement as he could not find a better candidate for the title of Fifth at that time. The Kage stand equally with the rulers of their countries, oversee the activities of their villages, and are the leaders of ninja society. They typically are the ones who send the ninja teams out on their missions and make the decisions regarding the safety of the village. The five Kage are:

The Hokage (火影; Literally meaning "Fire Shadow") of Konohagakure.

The Kazekage (風影; Literally meaning "Wind Shadow") of Sunagakure.

The Mizukage (水影; Literally meaning "Water Shadow") of Kirigakure.

The Raikage (雷影; Literally meaning "Lightning Shadow") of Kumogakure.

The Tsuchikage (土影; Literally meaning "Earth Shadow") of Iwagakure.

The five Kage as of the Fourth Shinobi World War.

The term Kage is not used to just refer to any leader of any village. Only the leaders of the five great shinobi villages can have their leader referred to as a Kage. In the anime, Hoshigakure has unofficially dubbed each of its leaders the Hoshikage (星影; Literally meaning "Star Shadow"), signifying their ambition to be recognised as an equal to the five great villages. However, this title is only a name, and the five Kage do not recognise it as their equal.
Since the creation of jinchūriki, it has become tradition for the host to be selected from the family of the village's own Kage. In this way, the jinchūriki not only has strong ties of loyalty to village and their leader, but they also serve as as display of the Kage's might. For example, both Killer B and three of his predecessors are related to the Third and Fourth Raikage and Gaara is the son of the Fourth Kazekage.