Vendor is an  individual  or  company  that  sells  goods  or services  to someone  else  in  the  economic production  chain. An audit  is a  independent, systematic and documented process  for obtaining  audit evidence  and  evaluating  it objectively  to  determine  the  extent to which  criteria  are  fulfilled  and  also  work  done  in  the organization are in the given standards. 

Reference : 

Asian Journal of Pharmaceutical Research and Development. 2018