The document discusses integrating Zend Framework components into CodeIgniter by copying the Zend library files into CodeIgniter's third_party folder, creating a Zf loader library to load Zend components, and then demonstrating how to use Zend_Debug to dump an array for testing. Zend Framework was chosen because it is a component-based framework that is easy to integrate parts of into CodeIgniter. The integration allows CodeIgniter projects to leverage specific Zend Framework components when desired.