Final answer:
User acceptance testing is a critical phase in project development that occurs just before project sign-off, ensuring that the system meets user needs and is ready for rollout.
Step-by-step explanation:
The user acceptance testing phase of a project is a critical stage that typically occurs immediately before project sign-off. This phase is where actual software users test the system to make sure it can handle required tasks in real-world scenarios, according to the specifications. User acceptance testing is essential for gaining buy-in from stakeholders and ensuring that the system meets their needs before it is rolled out into a live environment. It serves to validate the end-to-end business flow and is largely the last step before the system is approved for rollout.