A use case captures a contract between the stakholders of a system about it's behavior.The use case describes the system's behavior under various conditions as the system responds to a request from one of the stake holders, called the primary actor.use case are fundamentally a text form, although they can be written using flow charts, sequence charts, petri nets, or programming languages.the use case, as a form of writing , can sitmulate discussion when a team about an upcoming system.

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