Abstract: A central web server is provided which stores tens or hundreds of thousands of media assets (such as still photographs, video, logos, advertising text, etc.) in a database which can be accessed over the internet by any number of authorised persons, each with a computer using a standard web browser. The central web server is programmed to allow not only the creation of an advertisement on-line through the selection, assembly or modification of appropriate media assets, with a realistic on-screen simulation of how the published advertisement will look, but also the actual delivery of the media assets to for example, a magazine publisher or television station. By integrating the media asset delivery process into the on-line advertisement creation process, a fully integrated system is produced which greatly increases the efficiency of the management and production of advertising campaigns.