Everything! Haha. A set decorator is the department head responsible for set dressing—the furniture, rugs, drapery, lighting, artwork, books, and all the lived-in details you see on camera. Working closely with the production designer and director, the set decorator researches the world of the story, sources and rents or builds the right pieces, manages budgets and crews, and styles the set so it feels believable and supports the character, time period, and tone. In short: production design sets the vision, and set decoration makes it feel real.