Abstract: A digital contents area displayed on a terminal is detected, and an area to be charged is calculated according to the detected area. A criterion for determining that a user reads the digital contents is a time during which the area of the contents is displayed. If the time is equal to or longer than a predetermined time, the displayed contents area is determined to be an area to be charged. There are two methods, a page-change button method and a scroll method, as a method that measures a contents display time for determining whether an area is to be charged.

Abstract: When digital contents sold to a user become useless to the user, the digital contents and the license of the digital contents are collected or purchased from the user so that a privilege such as discount sale of other digital contents or addition of discount points is granted to the user having the license.

Abstract: If a commodity desired to purchase is selected in a purchaser terminal, a list of users (information providers) having a purchase history of the commodity at a shopping site is displayed. The purchaser terminal exchanges messages in real time with an information terminal of an information provider selected from the list, and obtains information concerning the commodity (information provision). In the case where the purchaser purchases the commodity, its commodity ID and a user ID of the information provider are associated with each other and stored in a shopping site operation apparatus. After the purchase of the commodity, a comment and/or evaluation concerning the information provision are input. On the basis of the comment and/or evaluation, privilege is granted to the information provider. The comment and/or evaluation are reflected in information of the information providers.