UAT usually starts when the system integration testing is almost complete, and a minimal amount of viable product is ready. The goal of UAT is to engage the users across business groups, using the new system to run the business. This is also an opportunity to provide them with hands-on experience for learning the new system. The more testing that the users perform, the more comfortable they will be with using the new system. Unlike other types of testing that are done by experienced application consultants and testing teams, UAT is done by actual business users, and hence, planning and execution of UAT is very critical. The Test-planning guidelines and recommendations section of this chapter covers UAT planning and execution in detail.