Stakeholders answer the question: Who is interested in?

Stakeholder becomes a source of needs and requirements, key stakeholders define business motivation, targets, and approach. Since stakeholders could impact or affect the business, solution, or project, it is important to manage a list of the stakeholders.

BABOK provides definitions in BABOK Guide Appendix A Glossary:

• Stakeholder – A group or individual with a relationship to the change, the need, or the solution.
• Stakeholder needs / requirements – A description of the needs of a particular stakeholder or class of stakeholders that must be met in order to achieve the business requirements. They may serve as a bridge between business requirements and the various categories of solution requirements.