This document discusses effective testing using behaviour-driven development (BDD). It begins by explaining test-driven development (TDD) and how BDD aims to involve more stakeholders like product owners and quality assurance. BDD uses a language called Gherkin to write features and scenarios in plain language. The document demonstrates examples of Gherkin and how the PHP framework Behat implements BDD by mapping Gherkin steps to code. It also discusses how Mink allows automated testing by simulating browser behavior. In summary, the document promotes BDD as a methodology that improves communication between teams and allows testing software that matters to stakeholders.