A user story is a software system requirement formulated as one or more sentences in the everyday or business language of the user. User stories are used with Agile software development methodologies for the specification of requirements (together with acceptance tests). Each user story is limited, so it fits on a small paper note card—usually a 3×5 inches card—to ensure that it does not grow too large. The user stories should be written by the customers for a software project and are their main instrument to influence the development of the software.

While user stories, use cases and usage scenarios all serve the purpose to capture specific user requirements in terms of interactions between the user and the system, there are major differences between them.