Camera obscuras are basically darkened structures like a small room or even a box. The walls of the structure are solid ... you know, to keep out light. And the only light that does enter comes through a small hole located on one of the walls. Due to the laws of optics, what happens is that the scene outside of the box is projected onto the inside wall of the structure. It's amazing ... the colour and the perspective of the scene are maintained perfectly. For the purpose of this class, you really don't need to know the exact mechanics of why this occurs. What you do need to know is that this practice— projecting a scene exactly as it appears onto a different surface—was an important precursor for modern photography. So for several hundred years after its initial invention, scientists continued to improve the camera obscura. For example, scientists discovered that making a larger hole in the wall produced a clearer image. Additionally, a smaller, more, urn, portable version of the camera was created. But even then, they were still a ways off from having anything close to photography as we know it today. I mean, sure, the camera obscura was able to project a scene onto a different surface, but it wasn't captured on that surface. The next step was finding a way to create a permanent image. And the first advance in this direction didn't occur until 1727. That was when a German professor named Johann Schulze accidently stumbled upon the first photosensitive compound.