We've seen the first two waves of Content Management Systems (CMSs) as being the custom CMS that gave rise to the proprietary CMS. The custom CMS market is dead. The proprietary CMS is under a great deal of pressure from the third wave of CMSs....

...the Open Source CMSs.

The roots and direction of the Open Source movement are beyond the scope of this article. Open Source means several things, the most important of which is that the program itself is free to be copied and re-distributed under certain conditions. Open Source Software (OSS) is generally maintained and developed by the community that uses it. Involved users extend the functionality of the software in directions that are interesting or useful to them. These extensions are distributed among the community and the software's functionality grows. With that increased utility, hopefully the software gains new users and the market and community continue to grow.

All of these reasons culminate in the fact that open source CMSs like Joomla!, Wordpress and Drupal are pressing hard on the proprietary CMSs. Consider the following selling points:

The selling proposition is compelling: Greater extensibility, larger development community, and no direct software cost.

There are downsides to Open Source projects as well. The greatest risk is that of the volunteer developers losing interest and the project stagnating. This risk can be minimized by choosing a CMS that has a large enough mass of users that even if one or more of the original developers lose interest that there is a large enough market that someone will see the opportunity and step in to continue the development.