Scrum is an iterative process based on the empirical control of the current status of the project.
3 fundamental principles:
$$ \text{visibility} \rarr \text{inspection} \rarr \text{adaptation} $$
Those aspects of the process that affect the outcome must be visible to those controlling the process. It must be clear which functionalities are completed, modified, faulty, …
Information must be clear: when a functionality can be labeled as “done”?