Francesco Casetti advances a provocative hypothesis: instead of being prostheses that expand or extend our perceptions, modern screen-based media are in fact apparatuses that shelter and protect us from exposure to the world. Rather than bringing us closer to external reality, dominant forms of visual media function as barriers or enclosures that defend against the apparent threats and dangers that seem increasingly to surround us. Working with an original historical overview that begins with the Phantasmagoria of the late eighteenth century, then the shared interior spaces of the movie theater in the early to mid-twentieth century, and finally the solitary digital milieus of the present, Casetti traces the outlines of the protective “bubbles” that disconnect us from our immediate surroundings.