Acceptance testing means toget acceptance from the 
client.
   Two types 1.alpha:almost all near the completion of the 
dovelopment of the project the endusers are conduct this 
testing before going to the delivery.
 
              2.beta:this testing is conducted by endusers 
after delivery the project.

it refers to to the client requirment

ACCEPTANCE TESTING:- Its an activity of Testing whether the 
application is acceptable or not.