What are Polaroids?
Light is electromagnetic radiation whose rays moving in all orientations; light moving in only one orientation (one set of rays) is considered "polarized" light. If you stare at a light bulb, many different orientations of the rays of light are entering your eye; looking at that same light bulb's image in a pane of glass shows it to have much less glare, as only one set of reflected rays enters your eye. In the 1930's Edwin Land developed a process to embed in plastic many tiny organic crystals in the same direction which would polarize a source of light, and gave it the trade-name "Polaroid." He started his company, the Polaroid Corporation in 1937 and began manufacturing prisms, safety glass, and eye and sun glasses, and other useful "Polaroid" products, all of which would drastically reduce the glare of the sun or other light source. Another of his major inventions was a new type of camera. At the time, photography required the exposure of film, followed by its processing into a stable image through a series of chemical reactions. In 1947 Land developed a camera capable of developing photographs with the necessary chemical seconds after exposure with a special film; "Polaroid" eventually began to refer to these "instant pictures."
Asimov's Biographical Encyclopedia of Science and Technology, I. Asimov, pg. 596, 1964.