Bitumen is a light-sensitive hydrocarbon that hardens when exposed to light. It was famously used by Joseph Nicéphore Niépce in the early 19th century to create the world's first photograph, known as View from the Window at Le Gras. In early photographic processes, bitumen served as a photosensitive coating, allowing images to be captured permanently on a plate or surface. Its use is historically significant in the development of photography, demonstrating the chemical foundations of image-making before the advent of modern photographic materials.