What is the importance of a project plan?

Below are some issues that a Project Management Plan is expected to address.

1. Which project management processes will be used for this process, what the level of implementation for each of these processes will be, and what the inputs and tools and techniques for these processes are

2. How the changes will be monitored and controlled

3. What the needs and techniques for communication among the stakeholders are

4. How the project lifecycle looks, including the project phases if the project is a multiphase project

5. The lifecycle selected for the project at hand