The authoress follows the transformation of documentary photography from the beginning of the 20th century to the present-day. Two terms: 'a public document' and 'a private document' are introduced into the analysis. The first one is used with regard to the work of early and classical photojournalists (i.e. Lewis Hine or Jacob Riis) and the second is applied to the works of contemporary photographers. Often 'a private document' shows the images of current city and the urban life style of its authors. In conclusion, the idea of a photographical image as an objective evidence of life has turned into autobiographical narration of authors of pictures. What is more, documentary style of representation is systematically exploited in pop-culture and commercial production.