i* (pronounced "i star") or i* framework is a modeling language suitable for an early phase of system modeling in order to understand the problem domain. i* modeling language allows to model both as-is and to-be situations. The name i* refers to the notion of distributed intentionality which underlines the framework. It is an approach originally developed for modelling and reasoning about organizational environments and their information systems composed of heterogeneous actors with different, often competing, goals that depend on each other to undertake their tasks and achieve these goals. It covers both actor-oriented and Goal modeling. i* models answer the question WHO and WHY, not what.
In contrast, the UML Use case approach covers only functional goals, with actors directly involved in operations (typically with software). The KAOS approach covers goals of all types but is less concerned with the intentionality of actors.