Ivar Jacobson, the inventor of use cases and co-creator of component-based development, UML and RUP, and Alistair Cockburn, author of a popular book on use cases and also co-author of the Agile Manifesto, got together to unify, simplify and clarify the definition of a use case so that it is easier for people to learn, to write and to integrate with other currently popular techniques and approaches.
The same document is posted on both Ivar’s site here and Alistair’s site here.
We hope you find this unified foundation for use cases useful.
— Ivar Jacobson and Alistair Cockburn