The Terrasphere is the complete extension of human, and human derived cultural activities, through space and hyperspace. In the 34th C the Terrasphere spreads over nearly 500 light years of space around Sol. It includes, by definition human, derived AI and AI culture.
It's a sprawling and unruly place, filled with modded humans (tweaks), AIs, post humans, cyborgs & even a few trillion Primes. Broken into groups seperated by light years, ideology and technology there is eternal conflict.
And beyond the Terrasphere lies the uncharted starlanes and strange alien empires whose nature and motives are unknown.