"Raw" means the hair has never been chemically processed. No perms, no relaxers, no dye, no silicone coatings. It is exactly as it left the donor's head — which means the cuticle is still intact, the natural texture is preserved, and the hair responds to color, heat, and moisture exactly like your own hair would.
Most hair sold as "human hair" has been chemically processed to make it look uniform. That uniformity comes at a cost: the cuticle is stripped, the hair becomes brittle over time, and within months it looks nothing like it did in the bag. Raw hair does not do that.
Raw single donor hair that has never been touched keeps the natural curl pattern of that one donor, with hydrogen bonds fully intact. You get the hair exactly as it grew. That is the S. Riviere difference: not just raw hair, but untouched raw single donor hair.