The significance of User Acceptance Testing (UAT) in software deployment lies in validating that the software meets the end-users' needs and expectations before going live. UAT involves real users testing the system in a controlled environment, providing feedback on functionality, usability, and performance. This critical phase helps identify any issues or discrepancies from the original requirements, ensuring that the software is user-friendly and meets specified business criteria. Successfully conducting UAT minimizes the risk of post-launch issues, enhances user satisfaction, and leads to a more efficient adoption of the new system.