A use case diagram in the Unified Modeling Language

Unified Modeling Language

Unified Modeling Language is a standardized general-purpose modeling language in the field of object-oriented software engineering. The standard is managed, and was created, by the Object Management Group...

 (UML) is a type of behavioral diagram defined by and created from a Use-case analysis

Use-case analysis

A use case analysis is the most common technique used to identify the requirements of a system and the information used to both define processes used and classes which will be used both in the use case diagram and the overall use case in the development or redesign of a software system or...

. Its purpose is to present a graphical overview of the functionality provided by a system in terms of actors

Actor (UML)

An actor in the Unified Modeling Language "specifies a role played by a user or any other system that interacts with the subject.""An Actor models a type of role played by an entity that interacts with the subject ,...

, their goals (represented as use case

Use case

In software engineering and systems engineering, a use case is a description of steps or actions between a user and a software system which leads the user towards something useful...

s), and any dependencies between those use cases.

The main purpose of a use case diagram is to show what system functions are performed for which actor.