It's an Independent review for the purpose of assesing
compliance with requirements,specifications,standards.

A systematic and independent examination to determine 
whether quality activities and related results comply with 
planned arrangements and whether these arrangements are 
implemented effectively and are suitable to achieve 
objectives. 

It is indepenent assement of a project.
  To verify whether or not the project is in complience     
with appropriate polcies,procedures,standards,contractual 
satisfaction.
   An audit may include opeartional aspects of the project.

A regular investigation of the s/w installed on all the 
computers in  a company to ensure that it is licened or 
authorised.