Professional Scrum Product Owner, abbreviated as PSPO, is the scrum product owner certification awarded by Scrum.org. People who have passed PSPO I, achieving certification, demonstrate a fundamental level of Scrum mastery.
PSPO I certificate holders prove that they understand Scrum as described in the Scrum Guide and how to apply Scrum in Scrum Teams. PSPO I holders have a consistent terminology and approach to Scrum.
In the waterfall project management, requirements are gathered, scope documents are generated, approval of the customer is acquired, the project team starts to work on the project and after months of progress, the customer could see the outcomes of the project.
However, harsh competition in the market and especially shorter product lifecycles make waterfall project management methodologies impossible to adapt. Because, when an organization is developing a product or a new feature for an existing product, its rival might come out with a new product and the organization must adapt itself with these changing requirements rapidly which is not easy in waterfall project management methodologies.

In Agile Project Management, the product is evolved with small increments and new features added step-by-step throughout the project. This enables the customer to see the developing product and make alterations in the requirements earlier when needed.