What is digital photography? how is a digital photograph created? how has digital photography changed the art of photography?

Digital photography is a form of photography that uses cameras containing arrays of electronic photodetectors to capture images focused by a lens, as opposed to an exposure on photographic film. ... Digital images can also be made by scanning other printed photographic images or negatives.

Digital photography is a new way of photography. New cameras have "arrays of electronic photodetectors to capture images focused by a lens"
These kinds of photos are digitalized and kept in computers files. They are generally created by computer or mechanical techniques. The first cameras appeared in the 1990 and they were revolutionary. I changed the art of photography because it eases the photographer job, it replaced the typic film and the printing process which sometimes was complicated, took a long time and many images were lost in the way. 

The answer is a : varying the size of objects or subjects, so that some are smaller than others and the illusion of depth is created.hope this : )