What Is: The Product Backlog
The Wish List
The Product Backlog is widely considered to be a ‘wish list’ of sorts, because everything that will be added to the product, should originate (from the Development Team’s perspective) from the Product Backlog, and it may not all find its way into the product. For instance, there may be 573 Product Backlog Items on the current Product Backlog. These items will be of various sizes and in various states of ‘readiness’. Those items that never get refined, and consequently not brought to a state of ‘ready’, will likely never see the light of day (never be built). Hence, we call these items ‘wishes’. In short, if it is going to be added to the product, it should have been prioritized in the Product Backlog first.
A Transparent Artifact
The Product Backlog is ‘transparent’ in that it is open and available for everyone in the organization to view, and add Product Backlog Items to it. (In highly regulated environments, the transparency of this artifact may not be absolute.) The Product Backlog still belongs to the Product Owner, so the PO will still need to prioritize these items, but the organization at large should have access to the Product Backlog at all times.
An Unstable Artifact
Because new Product Backlog ITems can be added to the Product Backlog at all times, and because the PRoduct Owner should be reprioritizing the Product Backlog at all times, the Product Backlog is not a stable artifact. In fact, only the Increment can be considered stable (and for that matter, only until the next Increment is completed). Do not expect the PRoduct Backlog to look exactly the same way from day-to-day (unless you are the PO).