The world started because Chaos (darkness), Gaia (earth), and Eros (love) mixed together. These were 'gods' but not the “real” gods.
Chaos gave birth to Erebos and Night.
Ouranos and Okeanos sprang from Gaia. Ouranos' job was to protect Gaia, although later they became a couple. Ouranos and Gaia gave birth to the twelve titans, three cyclopes, and three giants with one hundred hands. Ouranos was unhappy because of his children, and decided to hide then in (or on) Gaia (or earth.). Originally Gaia was unhappy with that, but later decided it was okay. Then she decided that she'd have to get rid of her husband, and supplied one of her sons, a titan named Kronos, with a sickle. When Kronos cut off his father's private parts and killed him, part of him fell into the sea and created Aphrodite. From his blood came the Fates, Giants, and the Meliani nymphs.
Kronos took over the throne and married his sister Rhea. He then freed his siblings, and all were happy for a while. Then Kronos began to have his own children, and had the same fears his father did. He decided just to swallow them when they were babies to save himself the trouble of killing them later. Rhea, however, was unhappy with this, and she managed to hide her son, Zeus, from his father, and convince Kronos to swallow a rock instead. When Zeus got older, he killed his father, and released his (Zeus's) siblings from his father's entrails.