Behaviour-Driven Development (BDD) is an evolution in the thinking behind TestDrivenDevelopment and Acceptance Test Driven Planning.
It pulls together strands from Test Driven Development and Domain Driven Design into an integrated whole, making the relationship between these two powerful approaches to software development more evident.
It aims to help focus development on the delivery of prioritised, verifiable business value by providing a common vocabulary (also referred to as a Ubiquitous Language) that spans the divide between Business and Technology.
Wiki at: http://behaviour-driven.org/BehaviourDrivenDevelopment (DanNorth)
Wikipedia article at: http://en.wikipedia.org/wiki/Behavior_driven_development
Some implementations: Specter: http://specter.sourceforge.net/ RSPec: http://rspec.rubyforge.org/ NSpec: http://nspec.tigris.org/
See also BehaviorDrivenDevelopment (which developed separately). I suggest that we maintain both pages, because there is a wiki with this name. I have focussed most of the links onto the other one as it has a richer set. -- JohnFletcher