Plant in origin, made in a factory, and it drapes like something far more expensive.
Wood pulp, spun fine
Cellulose, usually wood pulp, dissolved and spun into filament. A plant raw material, a manufactured fiber. That is why it sits between cotton and polyester.
Cool, and it moves
More breathable than polyester, close to silk against the skin. Not as airy as linen, but it skims the body instead of holding a stiff line.
Rayon is the same thing
Viscose is a type of rayon. One fiber, two labels. And a satin piece can be viscose, polyester or silk, so the label is the only way to know.
Never wring it
Viscose loses strength when wet. Cold and gentle, press the water out, dry flat away from heat, iron low. Handled that way it keeps its drape for years.
The look of silk, easier upkeep
Much of our summer drape is viscose and satin-effect viscose. Skirts, fluid trousers, evening pieces that move.