The scope of a system can be representation by a system boundary. The use cases of the system are placed inside the system boundary, while the actors who interact with the system are put outside the system.
2. Use case :
A use case represents a user goal that can be archived by accessing the system or software.
3. Actor :
Actors are the entities that interact with a system. Although in most cases, actors are used to represent the users of system, actors can actually be anything that needs to exchange information with the system.
4. Association :
Actor and use case can be associated to indicate that the actor participates in that use case.
5. Generalization :
A generalization relationship is used to represent inheritance relationship between model elements of same type.
6. Include :
An include relationship specifies how the behavior for the inclusion use case is inserted into the behavior defined for the base use case.
7. Extends :
An extend relationship specifies how the behavior of the extension use case can be inserted into the behavior defined for the base.
8. Constraints :
Show condition exists between actors an activity.
9. Package :
Package a defined as collection of classes. Classes are unified together using a package.
10. Interface :
Interface is used to connect package and use-case. Head is linked with package and tall linked with use-case.
11. Note :
Note is generally used to write comment in use-case diagram.
12. Anchor :
Anchor is used to connect a node the use case in use case diagram.
