ISSD Fall 2010 School of Information, UC Berkeley

A use case is an outside-in or "black box" depiction of a system's functionality from the perspective of an "actor". Use cases define possible sequences of interactions or procedures between actors and the system that achieve some goals or otherwise result in successful outcomes for users (and often, other stakeholders). Text is a suitable format for specifying a use case but any text specification in "natural language" can easily be incomplete, inconsistent, or ambiguous, which is why "best practices" for writing text specifications include "simplified writing" and "business rules" (with controlled grammar, vocabulary, and logic flow).