JBehave is a Java-based framework supporting Behaviour-Driven Development (BDD), an evolution of Test-Driven Development (TDD) and Acceptance-Test Driven Developement (ATDD).
BDD aims to make development practices more accessible and intuitive to newcomers and experts alike, but shifting the vocabulary from being test-based to behaviour-based. It positions itself as a development paradigm, emphasising communication and automation as equal goals.
In BDD, the behaviours represent both the specification and the test cases.
You can find out more about Behaviour-Driven Development on the BDD wiki, or in the article Introducing BDD.