There are many countries within that of the continent. The very existence to that of a shinobi village means for them to have military power. This is how they hold and maintain advantages over rivaling villages and countries. Kages are the most important members of a village and can be known as somewhat of a president and unrivaled leader of that village, whcih is why they play a very important role for each village, for such cases as going to war and making decisions about sending who for what missions and for defending their own villages with strong strategies.

There are many Shinobi villages which are that of the Leaf, Sand, Mist, Cloud and Stone are the largest of all of the shinobi countries and are referred to as the large and powerful "Great Five Shinobi Countries". Within these five great countries are the Kages. If you belonged to another country and you the leader you would not be referred to as a Kage. The Kages names are Hokage, Mizukage, Raikage, Kazekage, and Tsuchikage, but are also known as "The Five Kages". If there has been more than one kage from a single village they all go by the same name, for example the Hidden Leaf Village has had 4 Kages and Naruto wants to become the fifth.

Below are the names of the Great Five Shinobi Countries and the country they are responsible for:

Hokage
Hokage is the name of the Kage of the Hidden Leaf Village. Hokage can be translated to: Fire Shadow

Kazekage
Kazekage is the name of the Kage of the Hidden Sand Village. Kazekage can be translated to:: Wind Shadow

Raikage
Raikage is the Kage of the Hidden Lightning Village. Raikage can be translated to:: Lightning Shadow

Mizukage
Mizukage is the kage of the Hidden Water Village. Mizukage can be translated to: Water Shadow

Tsuchikage
Tsuchikage is the Kage of the Hidden Earth Village. Tsuchikage can be translated to: Earth Shadow.

These Kages are the most important ninjas of their respective village. As written above the Kages are the leaders of their villages and are responsible for their choices for war and handling things that would be needed to be handled by what would be a Governor. The Kages for each village only are used in a mission when that mission is a rank A mission where even a Kage is required to participate with that of the Jounin.