The general definition of an audit is an evaluation of a person, organization, system, process, enterprise, project or product. The term most commonly refers to audits in accounting, but similar concepts also exist in project management, quality management, water management, and energy conservation.

Audits are performed to ascertain the validity and reliability of information; also to provide an assessment of a system's internal control. The goal of an audit is to express an opinion of the person / organization / system (etc.) in question, under evaluation based on work done on a test basis.

Due to constraints, an audit seeks to provide only reasonable assurance that the statements are free from material error. Hence, statistical sampling is often adopted in audits. In the case of financial audits, a set of financial statements are said to be true and fair when they are free of material misstatements - a concept influenced by both quantitative (numerical) and qualitative factors. But recently, the argument that auditing should go beyond just True and fair is gaining momentum. And PCAOB has come out with a concept release on the same.