Alpha testing and beta testing are done under UAT technique. 

Alpha testing:-If the build is tested successfully with all
system testing technique and security testing they will
deploy that build in one the server located at developers
site. Once deployed in developers site ( company developed)
they start doing final round of testing to check that the
application is meeting the requirements and user
needs(Business) . SO testing done at developers environment
is called ALpha Testing.


Beta Testing:- Once the above ALpha testing is done they
will deploy this build in clients location on clients
machine which we call it as main production machine. Once
deployed there testing done with all business techniques.
Here in Beta testing all business related or few user come
and test the application and check whether they can complete
there own business. One the users satisfy then only it will
be lanched in market.