The customer presents the user stories to ensure that the team understands what is to be done. The most effective way to understand a requirement is to discuss it.
This begins the exploration phase of the iteration plan: explaining and understanding the stories to be done. The customer has selected the stories to be implemented during this iteration. She reads each story card, and the team members ask any questions they have until they understand the story. Each team member is responsible for having a good grasp of what the story requires.