Over the next few weeks, I will blog about the architecture of CiviCRM and some basic principles that we follow in the design/coding phase. In this series I’ll also talk about how we integrate with Drupal/Joomla and the scalability/performance/memory bottlenecks in CiviCRM.
CiviCRM is built on top of some incredibly powerful open source toolkits. They include:PHP, we use PHP 5.1 for development and will probably switch to PHP 5.2 in the next few weeks as our primary development platform. We restrict ourselves with the features that we use in PHP 5 to enable an auto-translation of the code to PHP 4. I suspect we will drop support for PHP4 around the time we release CiviCRM 2.0 :)