An audit is a review of a system, document, organization, or anything, usually done by an independent, uninvolved party. The purpose is to verify that the subject of the audit was completed or operates according to approved and accepted standards, statutes, regulations, or practices. Therefore the audit is an important part of management.

Some examples are:

• Telecommunication audit
• Financial audit
• Performance audit
• Information Technology Audit
• Academics - Completion of a course of study for which no assessment is completed or grade awarded; especially audit is awarded to those who have elected not to receive a letter grade for a course in which letter grades typically awarded. This technique is often employed by individuals who wish to take a specific course without the risk of under-performance resulting in a poor or failing grade; this can be helpful when reviewing a long-unstudied subject, when first beginning the study of a discipline wherein one has little experience or confidence, when taking a course merely for enjoyment with no need or desire of academic credit, et cetera. Auditing is generally an option at institutions of higher learning (colleges, universities) rather than grammar school (K-12).
• The Scientology practice of auditing. See Scientology beliefs and practices.