The Culture was an association of sapient species in the Milky Way galaxy in Iain M. Banks Culture Universe.
It was founded by about eight pan-human species around the 76th century BCE. The Culture's territory encompassed its member ships and space habitats spread throughout the galaxy. Orbitals rather than planets provided the most living space and terraforming was not done due to its ecological horrors.
Minds were sophisticated and sapient AIs that were used for administration and planning and were the brains of spacecraft and space habitats. They became the leaders of The Culture. The computational and memory components were particularly dense and were located in subspace dimensions created by internal warp units. Power was provided internally and field generators were used for propulsion.
The Culture was a post-scarcity economy, and was materially self-sufficient. It had productive capability whose capacity exceeded material needs which were readily available from interstellar sources. The Culture enjoyed a universally high standard of living and even a hedonistically-oriented lifestyle enabled by technology.
50 trillion people lived in the Culture in the 29th century. They had life expectancies of about 400 years; 300 of these were spent in a youthful physical state of slow aging, with accelerated aging toward the end. Options besides death included biological immortality and rejuvenation; very few chose outright immortality.
Minds and individuals (up to whole civilizations) can become the Sublimed, in which they transcend to higher dimensions beyond four (dimensions 8-11 of the 11-dimensional space). Subliming is one of the possible end points of a civilization, if extinction or a collapse into barbarism is avoided. Sublimed species become godlike with powers that include matter manipulation, omniscience and notably, the ability to tap into "gridfire" which is the channeling of the energy grid into real space, using for interdimensional communication or travel. The Sublimed can also progress into more powerful beings.