Behaviour Driven Development (BDD) is a software development approach that emphasizes collaboration between stakeholders in a software project such as developers, quality assurance analysts, business analysts, stakeholders, and managers. A Behaviour Driven Development (BDD) developer is a software developer who practices this approach in their work. Here's a detailed description of what a BDD developer does: . **Collaborative Planning**: BDD developers work closely with all stakeholders to understand the business needs and the behaviour of the system that needs to be developed. They facilitate discussions to encourage collaboration and to ensure that everyone has a shared understanding of the project. . **Defining Behaviour**: They define the expected behaviour of the system using scenarios in a simple, clear language which is understandable by all stakeholders. These scenarios describe what should happen in a certain situation and the expected outcome. This is often written in a Given-When-Then (GWT) format. For example, "Given a user is logged in, when they click on the 'logout' button, then they should be logged out and redirected to the login page." . **Test-Driven Development**: BDD developers use these scenarios to drive the development process. They use them to write automated tests that can verify the behaviour of the system. These tests serve as an executable specification for the system and a measure of progress. . **Implementation**: Once the tests are written, BDD developers write the code that makes the tests pass. The focus is on satisfying the behaviour defined in the scenarios rather than on the implementation details. . **Refactoring**: After making the tests pass, BDD developers refactor the code to improve its structure and maintainability without changing its behaviour. . **Continuous Integration**: BDD developers often work in short iterations and integrate their work frequently to catch problems early and to ensure that the software is always in a releasable state. . **Feedback and Iteration**: BDD developers use the feedback from the tests and from the stakeholders to guide their work. They continuously refine and extend the behaviour of the system in response to changing requirements and feedback. In summary, a BDD developer's role involves fostering collaboration, defining and implementing behaviour, and continuously integrating and iterating on the software. They use scenarios as a common language to bridge the gap between technical and non-technical stakeholders and to ensure that the software developed aligns with the business needs.