The basic idea behind Content Management Server is simple: create a Web site within a Web site, where each page has an alter ego that, when displayed, shows controls that allows different types of content to be altered. What was text in the "normal" view of a Web page becomes an edit control in the alternate view. What was a picture in the "normal" view of a Web page becomes an image chooser control in the alternate view. Taken together, these alternate views comprise an authoring mode for the Web site, built right into the Web site itself.
Generally speaking, in order for a Web site to be successful, its largest group of users needs to be the general public, or whatever broad class of users for whom the Web site was created. In Content Management Server terminology, such users are called "subscribers." They subscribe to the Web site. In cases where subscriptions are free, there are no sign-up procedures, and the Web site is on the Internet, the Web site is allowing everyone to be a subscriber.