This program is called Content Management System (CMS).

With CMS, you can login to administrator area and edit your content using a simple text editor similar to Microsoft Word.

It has power to manage hundreds or even thousand of pages like any other portal.

CMS websites is more expensive to build than static HTML, however it has more features that will benefit you in a long term.

You can self-manage your contents, upload images, link your files with an easy step. This approach will reduce your website maintenance expenditure dramatically.