What is photography

U can find a lot difination photography in the web such as :

              the act of taking and printing photographs
              the process of producing images of objects on photosensitive surfaces 
              wordnetweb.princeton.edu/perl/webwn

process, activity and art of creating still or moving pictures by recording radiation on a sensitive medium, such as a photographic film, or an electronic sensor. ...
en.wikipedia.org/wiki/Photography

and by all means to understand the photography  properly is to be a photographer, and photographer can define as :

someone who takes photographs professionally
wordnetweb.princeton.edu/perl/webwn

person who takes photographs using a camera. A professional photographer uses photography to earn money whilst amateur photographers take photographs for pleasure and to record an event, emotion, place, or person.                        

en.wikipedia.org/wiki/Photographer

and there also catogarized such as street photography, documentary photography, fashion photography, wedding photography, war photography, photojournalism, and commercial photography.