Camera obscura (lat. Dark room), is basically any dark area in which, through a small opening, a light comes in to. It was used for drawing and entertainment and it was one of the discoveries that led to development of modern day photography. Basis of how the camera obscura works are very simple. It revolves around a central projection, same principle that human eye relies on to create image. Beams of light, that normaly bounce off objects in every direction, go through a small hole on one side of the camera obscura and project the image of those same objects on an opposite surface (screen). Projected image is turned upside down, same as in human eye. If you place a light sensitive material on the screen (photo-film, photo-paper...) and expose it to light (opening a hole) which can take anywhere from few minutes to few hours, we get sort of a recording on a photosensitive material which can later on be made in to a photograph. Classical black and white photographs are developed in the dark room. Every positive of the photograph is made by shining a light to the negative with the amplifying device. This creates a latent image which needs to be developed in the developing liquid for a certain period of time with occasional nudging of the pot. Developing process is stopped in a stop bath and udnergoes a fixer treatment which prevents the picture of becoming yellow. After baths, the photograph is dried out. In the proces there are a lot of arbitrary factors which take careful choosing so we get a better photograph (sharp, right lightening, not yellow, straight...).