Here at Business Promotion, we generally use the WordPress content management system (CMS) as a framework for building client websites. Rather than build each page of the website individually, we use WordPress to dynamically combine theme elements (such as the background, menus, etc., that are the same across multiple pages) with the content (text and images unique to a particular page).
WordPress is probably the most popular CMS program in the world, but we didn't choose it because of popularity. We chose it because:
Reasons 1 and 2 are important to us as website developers, while reason number 3 is important for our clients. While we here at Business Promotion are always happy to make website changes for our clients, some people like the ability to log into their websites and make minor changes to the content themselves. WordPress is easy enough to use that pretty much anyone who has used a word processor can instantly understand what to do.