1) Behaviour-driven development (BDD) is an agile methodology that focuses on delivering working, tested software through collaboration between developers, testers and stakeholders.
2) BDD implements an application by describing its behavior through features and scenarios written from the perspective of stakeholders. Stories, acceptance criteria, executable examples and other tools are used to define requirements and guide development.
3) BDD aims to produce software that provides tangible value to stakeholders by being delivered incrementally, being easy to deploy and manage, and by adapting quickly to feedback through frequent testing and deployment.