Many companies have large websites that require management of 100,000s and even millions of content items (web pages, images, documents or other content items).  Traditionally, editing a web involved displaying the web site in a special preview window that altered how the web page looked when compared to how the web page would look to an external browser.  For example, the preview window would include sections of text such as “edit text in this box” between text boxes.  Because the instructions “edit text in this box” does not appear in the final web page (e.g., as seen by a site visitor), the user editing the web page had a distorted view of what the web site looked like.  In order to see what the web site really looked like, the user would have to open the page with a browser or enter a separate viewing mode.  This made managing edits cumbersome. 
While some systems allowed the content of the web page to be viewed while the web page was being edited, these systems typically inserted editing tools between the content components.  This caused the positions of the components and other aspects of the web page format to change in comparison to the actual production format of the web page.  In order to view the production format of the web page, a preview option was provided in which the editing tools were removed to allow the web page components to be viewed in the final production format.  Having to switch between the editing and preview environments, however, was inefficient and unwieldy.