What is User Acceptance testing (UAT)

There are two type of testing for User Acceptance Testing(UAT)
Alpha Testing and Beta testing.
Alpha testing :It will perform in internal company only, Here few developers, Testers and client will involve in this. They will create an virtual environment(like real time environment) in the company itself and they will conduct a testing in the presence of client.
Beta Testing :It will perform in client place,here few developers, Testers and client will involve here ,it will conduct by Client in real environment with real time data.