Behavior-driven development (BDD) involves naming software tests using domain language to describe the behavior of the code.

BDD involves use of a domain-specific language (DSL) using natural-language constructs (e.g., English-like sentences) that can express the behavior and the expected outcomes.

Proponents claim it encourages collaboration among developers, quality assurance experts, and customer representatives in a software project. It encourages teams to use conversation and concrete examples to formalize a shared understanding of how the application should behave. BDD is considered an effective practice especially when the problem space is complex.

BDD is considered a refinement of test-driven development (TDD).^[vague] BDD combines the techniques of TDD with ideas from domain-driven design and object-oriented analysis and design to provide software development and management teams with shared tools and a shared process to collaborate on software development.

At a high level, BDD is an idea about how software development should be managed by both business interests and technical insight. Its practice involves use of specialized tools. Some tools specifically for BDD can be used for TDD. The tools automate the ubiquitous language.

BDD is a process by which DSL structured natural-language statements are converted into executable tests. The result are tests that read like acceptance criteria for a given function.

As such, BDD is an extension of TDD.

BDD focuses on: