In conventional sense, Audit is refer to verification and scrutiny of documents, transaction and events and processes in order to verify facts and draw conclusions considering the correctness of recording of facts and the efficiency of a system under study.
For Central Excise concern, Audit is refer to scrutiny of the records of Assessee and verification & examination of the actual process of manufacturing of goods, classification of goods, correct valuation, measurement, proper usage of exemption notifications, export of goods, remission of duty, payment of duty, etc. with a view to check that whether the Assessee is enable to paying the Central Excise duty correctly and in timely and following the prescribed procedures.
For Service Tax concern, Audit is refer to examination of scrutiny of the records of Assessee and verification of the real provision of services, realization of sale proceeds, correct classification of service, timely discharge of tax liability, timely submitted of returns / information etc. with a consider to check that whether the assessee is enable to paying the Service Tax correctly and following the prescribed procedures.