Light sensitive emulsion
Any emulsion capable of recording an image due to the action of light. At the heart of the photographic system is the ability to convert light into density. In conventional photography this is achieved by using the light energy to break silver halides into silver metal and the halide. The quantity of silver metal produced provides the density in proportion to the energy of the total amount of light during exposure.
A light sensitive emulsion is the binder that holds the silver halide in place before exposure. After processing the emulsion is is no longer light sensitive but remains as the binder holding the final image.