A fact check is an assessment of whether a statement is true or false. It is usually conducted by journalists or researchers at a newspaper, magazine, radio station or TV channel. Generally, the journalist will supply a near-final draft of the article to the fact-checker, who then annotates the document with details and sources. Annotations can be made in the margins of a printed copy, or as footnotes or comments in a digital file. The fact-checker may also add a table of contents with the names and locations of each source, as well as a list of the key conclusions that should be made clear to readers.

Ideally, the fact-checker will be able to complete the process of verifying each claim as quickly as possible. This can be done by using a checkmark, a slash or another symbol to highlight each claim that is confirmed as true in the source material. In some cases, the entire article may need to be re-checked to address all of the factual errors in it.

Unfortunately, this ideal does not always align with reality. Journalists and editors sometimes tinker with the text after the fact-checker has begun working on it, which can be frustrating to the checker. Also, in some dangerous places (like India), it can be extremely difficult for fact-checkers to get their work done. As a result, the number of fact-checking sites in these countries has declined dramatically. To learn more about the state of fact-checking around the world, read this article by Reporters’ Lab researchers Mark Stencel, Erica Ryan and Joel Luther.