Joomla! is an award-winning content management system (CMS), which enables you to build Web sites and powerful online applications faster. Many aspects, including its ease-of-use and extensibility, have made Joomla! the most popular Web site software available. Best of all, Joomla is an open source solution that is freely available to everyone.
WordPress frameworks are becoming increasingly popular to build themes with. They allow for rapid development based on best practices, without the need to reinvent the wheel each time you design a new theme.