Short answers, pulled from the story.
In Greek cosmogony, Chaos refers to the first thing to exist, a vast void or gaping abyss that preceded the ordered cosmos. The Greek word kháos means emptiness, vast void, chasm, or abyss, derived from verbs meaning to gape or be wide open.
Hesiod, in his Theogony, states that Chaos was the first thing to come into being, with Erebus and Nyx unambiguously born from it. Aristophanes also depicted Chaos as the starting point of creation in his comedy Birds.
In the Timaeus, Plato used the term chôra rather than chaos, describing it as shapeless space in which material traces of the elements moved in disordered motion. He defined chôra as "a receptacle of all becoming, its wetnurse, as it were," a container for the creative act of the demiurge, the world-maker.
Dutch chemist Jan Baptist van Helmont coined the term gas in the 17th century directly from the Paracelsian notion of chaos. The letter g in gas reflects the Dutch pronunciation of that letter as a spirant, the same sound used to pronounce the Greek letter chi in kháos.
Paracelsus, who lived from 1493 to 1541, used chaos synonymously with the term classical element, because he understood primeval chaos as a formless congestion of all elements at once. He identified Earth as "the chaos of the gnomi," the element through which gnomes move as freely as fish through water.
In the Gnostic On the Origin of the World, dated to the late 3rd century AD, Chaos was not the first thing to exist. It formed from a shadow cast when Sophia, a figure of divine wisdom, reached toward a primordial light. From that Chaos, every deity including the Demiurge was born.