Collaborating with the product owner
The product backlog is generally prioritized by the product owner, due to the fact that they have a clear understanding and vision of the business requirements. Even though this is a given, the product owner does not always fully understand the implications of developing their requirements. Therefore a good estimation can assist the product owner through insight related to the level of complexity and effort required for each item on the backlog, helping them prioritize tasks more efficiently.
Questions are a common occurrence within the estimation process, they are usually related to product requirements and user stories, questions are good as they help the entire team understand the scope of the work. The answers to these questions enable the development team to break down the tasks into manageable pieces of work, show potentially hidden areas of work to the product owner and finally assist in the ordering of tasks from the backlog.