The Definition of Done (DOD) is a formal description of the state of the Increment when it meets the quality measures required for the product. It helps avoid rework by stating, upfront, what the team needs to do to build-in quality.
When quality slips, defects and rework increases, it’s important to look at the Definition of Done in the Retrospective.
Improving the Definition of Done reduces rework and defects by improving quality. The longer your Definition of Done the more work your team will need to deliver.
For non-software teams, rework means a focus away from delivery of value.