00: A few words from our summoner
Glossary of Terms
SPIRA: The world Yuna comes from. (Latin for Breath (inspiration))
YEVON: The religion that governs most of the world, including the summoning process. Its primary focus is atonement for the Machina War between two city-states (Bevelle and Zanarkand) and so it judges which machines people can use and which they cannot (which is just about everything but the blitzball sphere).
SUMMONER: A person willing to give their lives for the sake of Spira. They call upon the Final Aeon which can kill Sin but the summoning kills them in turn.
GUARDIAN: People that a summoner selects to protect them on their way to destroying Sin.
SIN: The monster that attacks Spira constantly. If a summoner kills it, it is reborn again after a few years time.
CALM: The period of time between the Sin's death and Sin's rebirth. It's a period of peace.
FAYTH: Those that pray to Yevon to take their lives from their still living bodies. These spirits are those that the summoner connects with in order to call forth an aeon. The fayth ready the summoner's mind for the Final Aeon.
AEON: A huge summoned beast that protects the summoner. Due to the fayth, the summoner and her aeons have a very close connection with each other.