the object of the invention is to perform a constructive exchange of information between a user and a provider of products in virtual reality . a user places a product 154 that he is considering buying in a cart , designates product providers , and gives notification thereto of the cart contents . a designated product provider 153 , by seeing the cart contents , can learn in what products the user is interested . the product provider 153 can provide to the cart from which the designation arose additional information 155 , such as advertisements for its products . the user , by receiving various types of additional information from a product provider that he trusts , can find products that meet his desires , and can enjoy more satisfactory network - based shopping .