Who is Styx from Theogony and Works and Days and what is their importance?

Styx is the river daughter of Ocean. Her children by Pallas are Zelus, Nike, Cratos and Bia. When Zeus fights the Titans he offers privileges to any of the gods who will fight with him. Styx offers to help first, and as a reward her children dwell in Zeus' house. To swear by the river Styx is the greatest of oaths among the Greek gods. If a god lies and is forsworn by these waters, they spend a year prostrate and breathless without access to ambrosia and nectar. This is followed by nine years of exile from Olympus.