Use cases are one of the excellent tools for representing functional requirements of a system. Use case modelling refers to modelling of system's functions in terms of business events (use cases), who initiated the events (actors) and how does system reacts to those events (Whitten J.L, 2007). Use case models are usually represented as use case diagrams in conjunction with use narratives which describe each event in detail and how does user interact with the system in course of that event.
Below is an example of a use case which describes a common technology tracking system in a company. The approach followed is pure system analysis and representation of requirements in terms of business requirements and use case models.
References:
1. Whitten, Jeffery L., and Bentley, Lonnie D. (2007). System Analysis
and Design Methods (7th ed). New York, NY: McGraw-Hill
Companies, Inc. ISBN 0–07–305233
and Design Methods (7th ed). New York, NY: McGraw-Hill
Companies, Inc. ISBN 0–07–305233