A Server is a computer on the Internet that sends web pages to the machine that requests them for display in a web browser window. Servers do more than just serve, they can also process information before they send back the page. The information is processed using cgi-scripts before it is sent back to the machine that made the request.

In Opus this means that the server can send back information to the publication. Information is sent to and from the server using the Post Web Data action.