The Project Management Body of Knowledge (PMBOK) defines the following 10 knowledge areas which are essential for effective project management:

1. Project Integration Management: This area involves coordinating all aspects of a project, ensuring that the various elements work together smoothly.

2. Project Scope Management: It focuses on defining and controlling what is and is not included in the project.

3. Project Schedule Management: This area is concerned with ensuring that the project is completed on time.

4. Project Cost Management: It involves planning, estimating, budgeting, and controlling costs so that the project can be completed within the approved budget.

5. Project Quality Management: This area ensures that the project will satisfy the needs for which it was undertaken.

6. Project Resource Management: It involves identifying, acquiring, and managing the resources needed for the successful completion of the project.

7. Project Communication Management: This area ensures timely and appropriate planning, collection, creation, distribution, storage, retrieval, management, control, monitoring, and the ultimate disposition of project information.

8. Project Risk Management: It involves identifying, analyzing, and responding to project risks.

9. Project Procurement Management: This area is concerned with the processes necessary to purchase or acquire products, services, or results needed from outside the project team.

10. Project Stakeholder Management: It involves identifying the people, groups, or organizations that could impact or be impacted by the project, analyzing stakeholder expectations and their impact on the project, and developing appropriate management strategies for effectively engaging stakeholders in project decisions and execution.

These knowledge areas cover a wide range of competencies that project managers need to master in order to lead projects successfully from initiation to closure.