Who is The Ousters from The Rise of Endymion and what is their importance?

The Ousters are a large group of post-humans and aliens that turned away from planetary life, preferring to live solely in space. Ousters are the descendants of the humans who were sent on deep space seedships and discovered the only way to survive the hostile environments into which they were sent was to incorporate nanotechnology and genetic engineering into their race. The Ousters are humanity's future.