CMS stands for “content management system”. In short, they are frameworks that websites are built on so that non-technical users can manipulate their content and presentation without the aid of technical personnel. For example, a blogger can post an article without knowing how to program.

There are a variety of CMS systems, and each system is built with a certain paradigm in mind that is usually better for one kind of website or another. For example, WordPress is easier for non-technical users to understand, and it’s simpler in general, so the cost of producing a site is significantly lower. However, WordPress isn’t very flexible, so any kind of uncommon functionality will require reverse engineering and wasted hours, thusly increasing the cost of labor. Drupal, however, favors complexity and functionality over simplicity and form. Joomla is another CMS that’s right down the middle of the prior two. Choosing the right CMS for your website is crucial, because it has an effect on its form, security, scalability, and most importantly, functionality.

In summary:

1. Drupal allows for more flexibility, but is more difficult to use. It is best suited for large web-communities or web-stores that require scalability over time.
2. Joomla is less complicated than Drupal, but is much less flexible. It is best suited for medium sized projects.
3. WordPress is the simplest of the three, and the least flexible. It is best suited for simple blogs or static sites that don’t require much scalability over time.

There are more CMSs that aren’t listed here, namely Magento. It’s strictly a web-store, and it’s extremely robust, so much so that no one would ever require that much power, unless of course they were a mega-corporation doing millions of dollars in sales each day like Amazon or eBay. Other CMSs exist as well, but the majority of the market share goes to these four, and for good reasons.

To choose the correct CMS for your project, you must consider what features you might want to add now and in the future, and strike a balance between cost and functionality. I would recommend using Drupal to build a new web-store or web-community, WordPress to build a business-one-page or a blog, and Joomla for anything else that doesn’t fall into one of those two camps. Only use Magento if you have your own dedicated server and the sales volume to justify it.