In the common law legal system, an expungement proceeding is a type of lawsuit in which an individual who has been arrested for or convicted of a crime seeks that the records of that earlier process be sealed or destroyed, making the records nonexistent or unavailable to the general public. If successful, the records are said to be "expunged". Black's Law Dictionary defines "expungement of record" as the "Process by which record of criminal conviction is destroyed or sealed from the state or Federal repository." While expungement deals with an underlying criminal record, it is a civil action in which the subject is the petitioner or plaintiff asking a court to declare that the records be expunged.

A very real distinction exists between an expungement and a pardon. When an expungement is granted, the person whose record is expunged may, for most purposes, treat the event as if it never occurred. A pardon (also called "executive clemency") does not "erase" the event; rather, it constitutes forgiveness. In the United States, an expungement can be granted only by a judge, while a pardon can be granted only by the President of the United States for federal offenses, and the state governor, certain other state executive officers, or the State Board of Pardons and Paroles (varies from state to state) for state offenses.

Each jurisdiction whose law allows expungement has its own definitions of expungement proceedings. Generally, expungement is the process to "remove from general review" the records pertaining to a case. In many jurisdictions, however, the records may not completely "disappear" and may still be available to law enforcement, to sentencing judges on subsequent offenses, and to corrections facilities to which the individual may be sentenced on subsequent convictions.