An external auditor performs an audit, in accordance with specific laws or rules, of the financial statements of a company, government entity, other legal entity, or organization, and is independent of the entity being audited. Users of these entities' financial information, such as investors, government agencies, and the general public, rely on the external auditor to present an unbiased and independent audit report.

A financial audit is conducted to provide an opinion whether "financial statements" (the information being verified) are stated in accordance with specified criteria. Normally, the criteria are international accounting standards, although auditors may conduct audits of financial statements prepared using the cash basis or some other basis of accounting appropriate for the organization. In providing an opinion whether financial statements are fairly stated in accordance with accounting standards, the auditor gathers evidence to determine whether the statements contain material errors or other misstatements.