How is cellophane made and what is its purpose?

Cellulose from wood, cotton, hemp, etc. is dissolved in an alkali and carbon disulfide mixture to create Vicose. The Vicose is then extruded through a slit into a bath of diluted sulfuric acid and sodium sulfate which turns the Vicose into a Celluose film. The film is then passed through several baths to remove the sulfur, bleach the film, and to add Glycerin to prevent the film from becoming brittle. It's mostly used in food packaging.