In Dianetics and Scientology, auditing is a process whereby the "auditor" takes an individual through times in their current or past lives with the purpose of ridding the individual of negative influences from past events or behaviors. According to practitioners, auditing is meant to bring the individual to "Clear" status; thus, an individual being audited is known as a "preclear" or PC.

Auditing was invented by L. Ron Hubbard as an integral part of Dianetics, first introduced in 1950. In 1951, auditing also became a core practice of Scientology. The E-meter, a device to measure electrodermal activity, became an integral part of auditing in scientology. According to the Church of Scientology, "one formal definition of auditing is the action of asking a person a question (which he can understand and answer), getting an answer to that question and acknowledging him or her for that answer".

Hubbard claimed auditing provided many benefits including unsupported medical and psychological health effects. Since 1971, Scientology now publishes disclaimers in its books and publications declaring that the E-Meter "by itself does nothing", and that it is used specifically for spiritual purposes, not for mental or physical health.