All the sites that I build are built on the back of a Content Management System (CMS). A CMS is basically a program that allows anyone with access permission to update a website without any knowledge of programming.
The content managed includes computer files, image media, audio files, electronic documents and web content. The idea behind a CMS is to make these files available inter-office, as well as over the web. A Content Management System would most often be used as archival as well. Many companies use a CMS to store files in a non-proprietary form. Companies use a CMS to share files with ease, as most systems use server based software, even further broadening file availability. As shown below, many Content Management Systems include a feature for Web Content, and some have a feature for a "workflow process."
"Work flow" is the idea of moving an electronic document along for either approval, or for adding content. Some Content Management Systems will easily facilitate this process with e-mail notification, and automated routing. This is ideally a collaborative creation of documents. A CMS facilitates the organization, control, and publication of a large body of documents and other content, such as images and multimedia resources.
Wikipedia
Generally, I use the Drupal system as a CMS implementation. This is the best system presently available, in my opinion - IBM also agree with me(see here).