An audit is an objective examination and evaluation of the financial statements of an organization to make sure that the records are a fair and accurate representation of the transactions they claim to represent. It can be done internally by employees of the organization, or externally by an outside firm.
When performing an audit, an auditor will request access to the business' financial records. This includes the ledgers, lists of receipts and expenditures, bank balances, records of physical assets owned or leased and many other records. The auditor will also interview personnel and review the business' accounting system and its internal controls. In essence, the auditor will review any activity that affects the business' finances.