A system is disclosed for messaging over a data network, such as the Internet and interactive TV, which allows every registered user to generate and update one or more user portfolio(s) containing information relative to Providers and/or individuals of which the user is willing to view their messages. The messages are displayed inside the space of the webpage where usually banners are shown. The system may provide benefits to the user upon displaying messages with commercial value to him. The disclosed messaging system allows an easy and effective communication path between providers and users any time publicly or privately in the banner area of a web site, which does not occupy additional space on the user's browser, and does not require the user to load another application besides his browser.