Q1. purpose

- The purpose of packages is to illustrate the functionality of a software system and represent the different layers of a software system by illustrating the layered architecture of a software system.

- is the container for UML things, such as use cases or classes. It show system partitioning and occur during systems analysis or designed.

- use a folder symbol with the package name either in the folder tab oe centered in the folder.

example of package diagram:



source: http://www.agilemodeling.com/images/models/packageDiagramUseCases.jpg

This diagram shows the use of packages containing use cases to illustrate the functionality of a software system and represent the different layers of a software system to illustrate the layered architecture of a software system.