Excerpts taken from the Oxford Classical Dictionary:

The main divinity of the Greek Pantheon. Zeus, the Indo-European god of the bright sky, is transformed in Greece into Zeus the weather god, whose paramount and specific place of worship is a mountain top, Mt. Olympus. As 'the gatherer of clouds,' Homer, he was generally believed to cause rain. With the god of clouds comes the god of thunder and of lightning; a spot struck by lightning Is inviolable and often sacred to Zeus, "He who comes down". As the master of tempest, he is supposed to give signs through thunder and lightning and to strike evildoers, as at the beginning of his reign he struck the Giants and the monstrous Typhon. For the early archaic Greeks, Zeus had much more fundamental functions. According to the succession myth in Hesiod's Theogony, Zeus deposed his father Cronus, who had deposed and castrated his father Uranus; after his accession to power, he drew up the present world order. Thus Zeus became the ruler over both the other gods and the human world.

Excerpts taken from the Encyclopedia of Mythology, Eric Flaum:

The greatest and most powerful of all the Olympians, Zeus was born the third son of Cronus and Rhea. When Cronus' death was followed by an attack from Atlas and the Titans, Zeus freed the Cyclopes and the Hundred-handed Ones from Tartarus… and allowed the Olympians to prevail. Atlas was condemned to hold up the earth upon his shoulders for eternity. Zeus also punished Prometheus who passed the secret of fire (knowledge & enlightenment) to mortal men. Prometheus's punishment was to be chained to a rock where a vulture daily consumed his liver which would grow back each night. Eventually, Heracles would save Prometheus.