The purpose of this artifact is to provide a central document where any project team member can find the information on how the project will be managed. 

This artifact defines the parameters for project progress tracking and specifies the high-level objectives of the iterations and their milestones. Additionally, it describes how the project is organized and which roles are played by whom.

The project manager is responsible for developing the project plan, working very closely with the rest of the team. The project plan allows stakeholders and other team members to understand the big picture and, roughly, when to expect what level of functionality. It it also used for recording the lessons learned from the project.