The Question and Answer section for The Lightning Thief is a great resource to ask questions, find answers, and discuss the novel.
From the text:
"Even I am not old enough to remember that, child, but I know it was a time of darkness and savagery for mortals. Kronos, the lord of the Titans, called his reign the Golden Age because men lived innocent and free of all knowledge....
There is the Argus, the Illiad, and the Titans.
Zeus is God of the Sky and owner of the master bolt, the object whose theft catalyzes Percy’s quest. Zeus is temperamental and proud, and it is best not to cross him.