We are working with SCRUM now for more than a year. But I did my first SCRUM training a couple of days ago. Was a very interesting training with a lot of nice people. I the three days duration of the training, it never got boored.
One picture was especially impressive: it shows the product backlog as an iceberg. The story is the following.
The product backlog consists of epics (very large user stories), user stories and grains of sand. It is not necessary to detail and estimate epics until they become part of the release backlog.
And it is not necessary to detail user stories into grains of sand until they become part of the sprint planning. This picture is very nice and easy to memorize. Thank you DasScrumTeam.