PHP has become the most popular programming language from the last few years. It is a based programming language that supports dynamic applications. PHP is a very simple language, which is easy to learn and implement. This is more simplified as compare to Java or .net or any other programming language. Anyone can learn PHP within a short period of time. PHP can be easily embedded into HTML. PHP also costs less to programmers. Complex web applications can be easily created with PHP, with less efforts and small time period as compare to other programming languages.PHP runs on a linux web server and produce dynamic web pages. PHP supports all kind of custom web development. Today there are many open sources available in PHP, like Joomla, Drupal, OScommerce, Magento open source and many more. These open sources can be easily integrated in PHP and supports an efficient, cost effective and advanced web development.
As PHP is a dynamic web programming language, it works with a particular database system which is MYSQL. MYSQL is the most standard database to be used with PHP. MYSQL is one of the relational database management system(RDBMS) which stores all kind of operational data in it and make available this data on web when accessed.
In short PHP is totally a well suited language for development of complex dynamic applications.
Never tried Joomla, you seem to like it I'll give it a shot. I try to stay away from CMS's but they seem to be gaining in popularity.. Lot's of freelance jobs out there now for CMS edits
Joomla is growing very faster. Now most of the applications are being developed on CMS. Joomla is one of the best solution for CMS based applications.