TATs and UATs

It is good practice to control the quality of what is produced during a project.
In PRINCE2 this is done in MP2 once the product has been created, manufactured or otherwise assembled.

In other circumstances, these quality checks are often called TAT or Technical Acceptance Test. In reality, PRINCE2 refers to those as product approvals (this can be applied to both management and specialist products).

The method of control for the final product will depend of the environment and will be defined in the Project Quality Plan (IP1) and confirmed for each simple product in the Product Description (in PL2). This Product Description is then added to the Work Package and agreed between the Project Manager and the Team Manager (if there is one) or the Team Member who will do the work (this happens in CS1-MP1).
Once products have been approved, they still need to be accepted by the Project Board.
This happens at the end of each stage during the End Stage Assessment (in DP3) for each product created during the previous stage, and at the end of the project for the final product (in DP5).
These are often referred to as UAT or Users Acceptance Tests.