  in software and systems engineering, a use case is a list of steps, typically defining interactions between a role (known in unified modeling language (uml) as an "actor") and a system, to achieve a goal. the actor can be a human, an external system, or time. in systems engineering, use cases are used at a higher level than within software engineering, often representing missions or stakeholder goals. the detailed requirements may then be captured in systems modeling language (sysml) or as contractual statements. as an important requirement technique, use cases have been widely used in modern software engineering over the last two decades. use case driven development is a key characteristic of process models and frameworks like unified process (up), rational unified process (rup), oracle unified method (oum), etc. with its iterative and evolutionary nature, use case is also a good fit for agile development. == history ==  in 1986 ivar jacobson first formulated textual, structural, and visual modeling techniques for specifying use cases. in 1992 his co-authored book object-oriented software engineering - a use case driven approachjacobson et al, 1992. helped to popularize the technique for capturing functional requirements, especially in software development. originally he had used the terms usage scenarios and usage case â the latter a direct translation of his swedish term anvÃ¤ndningsfall â but found that neither of these terms sounded natural in english, and eventually he settled on use case. since then, others have contributed to improving this technique, notably alistair cockburn, larry constantine, dean leffingwell, kurt bittner and gunnar overgaard. in 2011 jacobson published an update to his work, called use case 2.0,  with the intention of incorporating many of his practical experiences of applying use cases since the original inception of the concept.{{cite web|url= http://www.irmuk.co.uk/ba2011/ |title=business analysis conference europ
1986_establishments_in_Sweden Agile_software_development Software_project_management Software_requirements Swedish_inventions Systems_Modeling_Language Unified_Modeling_Language