Turaga were leaders of the Matoran and protectors of the legends of the Toa. Turaga came into being when Toa fulfilled their destiny and chose to sacrifice their Toa power for the greater good. This act led to the transformation of Toa to Turaga. Once a Toa transformed into a Turaga, he or she lost the ability ever to wield Toa power or use Great Masks again. Turaga were able to master Noble Masks and had limited elemental abilities. Physically, they were slightly stronger than Matoran, but they were nowhere near as powerful as Toa. Turaga were generally wise and competent leaders, but they also showed themselves to be capable of resentment, deception, and lack of trust.
Each of the six villages on Mata Nui was ruled by an elder called a Turaga. As the oldest and wisest member of the village, the Turaga's job was to be sure the ancient legends were not forgotten. The Turaga worked together to protect the knowledge of Mata Nui's past as well as the prophecies about its future.
Since the Toa arrived on Mata Nui, the Turaga provided them with important information. The Toa learned about the Kanohi masks and the Bohrok swarms from the Turaga, and they came to rely on the Turaga's wisdom. However, it often seemed that the Turaga knew more than they were telling. There were caverns that they forbid any Matoran to enter, although they would not say why. Some of the Toa Nuva questioned why they were not told about the Bohrok before the swarms appeared on the island.
Turaga commonly wore Noble Kanohi Masks.
A Toa transformed into a Turaga could still have a destiny as a Turaga.
Turaga were able to create Matoran as needed. For example, if there were some massive project in a city that required more workers, Turaga could produce them.
As far as we know, Turaga in general did not always have two Matoran aides like the Turaga on Mata Nui did.
Turaga were not able to handle the power level of a Great Mask.