This document introduces Codeception, an open source PHP testing framework. It discusses different types of testing like unit, integration, functional, and acceptance testing. Codeception uses PHPUnit, Symfony browserkit, Selenium, and PhantomJS to test PHP applications. The document demonstrates running Codeception tests and provides examples of passing and failing tests. It also discusses how Codeception allows testing JavaScript-heavy applications using Selenium or headless testing with PhantomJS. Continuous integration and Docker/Vagrant are presented as ways to improve testing workflows.