Fact checking is the act of checking factual assertions in non-fictional text in order to determine the veracity and correctness of the factual statements in the text. This may be done either before (ante hoc) or after (post hoc) the text has been published or otherwise disseminated.
Fact checking before dissemination (ante hoc checking) aims to remove errors and allow text to proceed to dissemination (or to rejection if it fails confirmations or other criteria). Post hoc checking most often is followed by a written report of inaccuracies, sometimes with a visual metric from the checking organization.
The aim for ante hoc analyzed text is often external publication, as in journalistic endeavors. Several organizations are devoted to post hoc fact-checking, including FactCheck and PolitiFact.