The Agile Developer's Handbook

Step 2 – Make the work policies of the team explicit

Teams often handle this by placing entry and exit criteria for each column to make them transparent. This will look something like the following:

The policies form what is commonly known as the Definition of Done (DoD). The DoD is a checklist that the team applies to each work item. It is a way for the team to ensure they've completed the work item to a satisfactory standard and therefore ensure they are the baking quality of their product.