An audit is a verification of a company's accounts. Internal audits are checks carried out as part of the company's own controls. When used unqualified the word audit is usually taken to mean external audit: the examination of accounts by external accountants (auditors) that is required by law.

There are legal restrictions on who can carry out an audit. In the UK the auditor must be a member of (or, more commonly, a partnership of members of) one of a small number of professional institutes. They must also be authorised by their institute to act as auditors. The institutes are: the ICAEW, the ICAS, the ICAI and the ACCA.

The annual report of a company must be audited. The audited accounts include an auditor's opinion on the accounts.

The National Audit Office audits most public sector bodies in Britain. It is answerable to Parliament and independent of the government. The Audit Commission appoints auditors for NHS and local government bodies. Both bodies have a wider role in examining the effectiveness and efficiency of public services.

Audit has traditionally been regarded as a somewhat boring profession. Its profile has been significantly increased following accounting scandals such as Enron.