The most general definition of an audit is an evaluation of a person, organization, system, process, project or product. Audits are performed to ascertain the validity and reliability of information, and also provide an assessment of a system's internal control. The goal of an audit is to express an opinion on the person/organization/system etc. under evaluation based on work done on a test basis. Due to practical 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 and qualitative factors.

Traditionally audits were mainly associated with gaining information about financial systems and the financial records of a company or a business (see financial audit). However recently auditing has begun to include other information about the system, such as information about environmental performance. As a result there are now professions that conduct environmental audits.

In financial accounting, an audit is an independent assessment of the fairness by which a company's financial statements are presented by its management. It is performed by competent, independent and objective person or persons, known as auditors or accountants, who then issue an auditor's report on the results of the audit.

Such systems must adhere to generally accepted standards set by governing bodies that regulate businesses. It simply provides assurance for third parties or external users that such statements present 'fairly' a company's financial condition and results of operations.

Quality audits

Main: Quality audit

Quality audits are performed to verify the effectiveness of a quality management system. This is part of certifications such as ISO 9001.

Integrated audits

In the US, audits of publicly-listed companies are governed by rules laid down by the Public Company Accounting Oversight Board (PCAOB). Such an audit is called an Integrated Audit, and auditors have the additional responsibilities of expressing opinions on management's assessment of the firm's internal control, and on the effectiveness of internal control over financial reporting based on their (the auditors') own assessment.

Types of auditors

There are two types of auditors: ''

• Internal auditors are employees of a company hired to assess and evaluate its system of internal control. To maintain independence, they present their reports directly to the Board of Directors or to Top Management. They provide functional operation to the concern. Internal auditors are employees of the company so that they can easily find out the frauds and any mishappening.