There is provided a network system in which image data items are uploaded from a plurality of user terminals to a server and images are opened to public among the users. The system includes a category division unit configured to divide the works classified into the categories into a first group of works with each of which the counted browse request number of times is greater than or equal to a predetermined number, and a second group of works other than the works in the first group, and classify one of the first and second groups of the divided works as another category different from the categories.