Camera film uses silver halides (such as silver chloride, bromide or iodide) as the materials exposed to light. When the silver halide layer absorbs light, electrons within the layer attach to the halide crystals, creating what are known as sensitivity specks. Light accordingly effects chemical changes in the silver-halide layer, leaving a latent image on the film. When exposed film is placed in a developing agent, the surroundings of the sensitivity specks are converted to silver, as a result of which the exposed areas start to turn black, and the image begins to "be developed." This is why chemical agents that reduce silver halides to silver are known as "developers." Even with development, those areas not affected by light remain as silver halides. They are removed by placing the film in a different agent that dissolves silver halides, leaving only the black silver grains. This is known as "fixing." A negative, which is an image in which the areas exposed to light appear as shades of black, is thus made by first taking a photo to create a latent image on the film, then developing and fixing that image with chemical agents. If printing paper is placed beneath the negative, and light is shone on the negative, the negative's blackened areas show up as lighter shades. Whiter areas show up as darker shades on the paper when that in turn is developed and fixed. This is the principle of black-and-white photography.