The Sprint Burndown Report shows the progress within the Sprint toward reaching the Sprint Goal. It provides transparency about the current performance (burndown rate) and allows easy estimation if the Sprint Goal can be reached in time or if the team has to find additional measures to speed-up completion of the remaining activities.
Sprint Burndown Report/Chart
The initial Sprint Backlog defines the start-point for the remaining efforts. The remaining effort of all activities are collected on a daily base and added to the graph. In the beginning the performance is often not as good as predicted by the ideal burndown rate due to wrong estimations or impediments that have to be removed in order to get on full speed.