In Project Management, according to the Project Management Institute (PMI) and the Project Management Body of Knowledge (PMBOK), a stakeholder is defined as any individual, group, or organization that can impact, be impacted by, or perceive itself to be impacted by the outcome of a project.

Stakeholders can include individuals or groups both internal and external to the organization sponsoring the project. They may have varying degrees of influence, interest, and expectations regarding the project and its outcomes. Examples of stakeholders include project sponsors, customers, users, project team members, suppliers, regulatory bodies, and the general public.

Identifying and managing stakeholders is a critical aspect of project management as their support, involvement, and expectations can significantly impact the success of a project. Effective stakeholder management involves understanding their needs, expectations, and concerns, engaging with them throughout the project lifecycle, and addressing their interests to ensure project success.