What do all agile frameworks in common?

All agile frameworks have a fixed, moderate iteration length, a lightweight approach that allows self-organising teams to respond better to business needs, and recurring and increasing development. It is a term that is involved in software development methods.

Who owns the product backlog?

“The Product Owner is responsible for the Product Backlog, including its content, availability, and ordering.” You can read this line as reinforcing the idea the Product Owner should also do all these things. So, the Product Owner should write all the items on the Product Backlog.