What process groups does PMBOK distinguish?

PMBOK identifies five process groups in project management:

1. Initiating — processes related to defining and authorizing a project or its phase.
2. Planning — processes aimed at developing the project management plan, including defining objectives, tasks, resources, and timelines.
3. Executing — processes related to performing the work according to the plan.
4. Monitoring and Controlling — processes for tracking, analyzing, and adjusting the project to meet its goals.
5. Closing — processes for formally completing all work and closing the project.

These process groups help structure project management and ensure a systematic approach to achieving objectives.