Photography is, arguably, the most significant invention of the nineteenth century. Try to imagine a world without photographs. Today, photography is such a part of all our lives that we take it for granted. We are surrounded by photographic images - in newspapers and magazines, on cinema and television screens, in our homes, at work and on the streets. Since the public announcement of its invention 1839, photography has been both a window and a mirror; revealing and reflecting our lives, shaping our vision of the world and of worlds beyond our vision. Photography challenges time and space - capturing the present and preserving the past. It can even make the invisible visible – revealing what is too fast, too distant or too small for the naked eye to see. A photograph can be many things - family memory or work of art, scientific record or piece of evidence, useful tool or historical document. Photography’s many and diverse roles became evident within a remarkably short time of its invention. The enormous potential of the new medium was soon understood and its many applications realised or, at least, identified.