Unified Modeling Language. Standardized modeling language, which is used, for example, in software engineering to visualize structures, architectures, behavior, and processes. UML defines identifier for important terms and the possible relations between these terms.
Describes how a user (actor) uses a system to accomplish a task. In software engineering, a use case is a list of steps, which define the interactions between the actor and the system and lead to the goal.
User stories are often used in agile software development to define specifications from the users' point of view. In one or two sentences, written in everyday language, user stories capture what users need to do their jobs or what they require from a product. User stories are listed in a so-called product backlog and evaluated with the INVEST criteria.