What is a product backlog and who owns it?

The product backlog is an ordered list of everything known to be needed to improve the product: features, enhancements, fixes and technical work. It is the single source of work for the Scrum Team and it is never complete, because it evolves as the product and market are better understood.

In Scrum, the Product Owner is accountable for the backlog: developing and communicating the Product Goal, creating and clearly expressing items, ordering them, and making sure the backlog is transparent and understood. The Product Owner may delegate some of this work, but remains accountable. The Developers decide how much they can pull into a Sprint and estimate the items.

Good backlogs are ordered by value, risk and dependencies. The top items are small and clear enough to be worked on soon, while items further down stay larger and less detailed. Refinement is the ongoing activity of adding detail, estimates and order.