We find ourselves, still early in the 21st century, in an unprecedented era in the history of photography. The consumers of the developed world have, of course, had access to cameras of their own for decades and decades, but now almost each and every one of us walks around with a camera in our pocket. When a particular landscape, building, animal, human being, or other sight strikes our fancy, we capture it without a moment's hesitation — and, often, without having given a moment's thought to the technological and artistic history of the discipline we are, if for little more than an instant, practicing.