In ideal world people talk to each other, the vision of the product is clear, priorities are defined, everyone know what to do and there is no problems with such thing as 'backlog management'.
In real world we have 'mainstream agile' with frameworks that basically try to make waterfall from agile and... force you to use 'User Stories' with strictly defined format and 'deep' insight to the problem. You might say it's not so bad... However how many times you saw something like: 'As a user I want to be able to log-in so that I'm logged-in'? Or even worse, have you seen 2 years ahead backlog full of user stories like that? Yep, that's mean that it's high time for refactoring! User stories refactoring!
What you'll learn:
1. Step one: size. What to do if backlog is too big? (And so there is too many user stories to refactor).
2. Step two: size^2: What to do with 'fat' user stories?
3. Step three: content. Delete or not delete, it's a question!
4. Step four: identify value feature relation.
5. Step five: write it down!