What are gigantes?

In Greek mythology, the gigantes were a race of giants, children of Gaia or Gaea (Earth Mother) who was fertilized by the blood of Uranus when Cronus castrated him. The primordial Gigantes rose up in arms against the Olympians to end the reign of the Olympian gods but were defeated and buried beneath the Earth, where their writhing is supposed to cause volcanoes and earthquakes.