The Product Backlog is an ordered set of items that might be needed in the final product. In other words, it’s a kind of a wish list or a prioritised features list, containing short descriptions of all desired product functionality.
The Product Owner creates, maintains, and regularly re-orders the Product Backlog. He/ she describes it top items during the sprint planning meeting. He/she describes all items in a simple business language without technical specifications. The Product Owner uses the Product Backlog to adapt to emerging requirements, customer feedback, and market changes.