What is the purpose of a test completion criterion?

A test completion criterion is used to determine when testing activities can be concluded. According to the ISTQB Certified Tester Foundation Level Syllabus v4.0, setting test completion criteria helps in defining when the testing objectives have been achieved, which includes reaching a defined coverage level, running out of time or budget, or meeting the expected level of risk acceptance. These criteria are essential for ensuring that the testing process is concluded appropriately and resources are utilized effectively.