A blacklist (or black list) is a list or register of entities or people who, for one reason or another, are being denied a particular privilege, service, mobility, access or recognition. As a verb, to blacklist can mean to deny someone work in a particular field, or to ostracize a person from a certain social circle.
Conversely, a whitelist is a list or compilation identifying entities that are accepted, recognized, or privileged.
The term blacklisting may be used in a pejorative sense, implying that a person has been prevented from having legitimate access to something due to inappropriate covert actions of those who control access. For example, a person being served with a restraining order for having threatened another person would not be considered a case of blacklisting. However, somebody who is fired for exposing poor working conditions in a particular company, and is subsequently systematically blocked from finding work in that industry, is described as having been inappropriately and often illegally blacklisted. Blacklisting can and has been accomplished informally by consensus of authority figures, and does not necessarily require a physical list or overt written record.
Blacklisting can be formal or informal. In the employment setting, applicants who apply to numerous positions regardless of being qualified or not can soon be ignored during some or all subsequent applicant processes, This can be an informal choice made by one person or a shared formal response taken up by one office, and not an issue that would be described as blacklisting. In the past, blacklists of union members have been shared or circulated between multiple organizations to prevent hiring of employees who, rather than being incompetent, have been critical of management actions. People have been prevented from working for decades due to being on a blacklist; in some cases the information on the blacklist was false. 
According to the Henry Holt Encyclopedia of Word and Phrase Origins the word "blacklist" originated with a list England's King Charles II made of fifty-eight judges and court officers who sentenced his father, Charles I, to death in 1649. When Charles II was restored to the throne in 1660, thirteen of these regicides were put to death and twenty-five sentenced to life imprisonment, while others escaped.
They also point out that "whitelist" is not the opposite of a blacklist, but rather a list, often kept by unions, of people suitable for employment.
Credit card merchant accounts
Companies which have a payment card merchant account terminated, and their directors, are often added to a list referred to when companies apply for an account; they are then unlikely to be granted a new account by any provider. In the US the list is called TMF/MATCH.
Blacklisting by multiple providers is a systematic act by doctors to deny care to a certain patient or patients. It is done in various ways for various reasons; blacklisting is not new. In 1907 the Transvaal Medical Union in South Africa blacklisted patients if they could not pay cash in advance. In this case, there was a physical list kept by the community of physicians. A physical list is not necessary to blacklist patients but the effect is the same.
In computing, a blacklist is an access control system that denies entry to a specific list (or a defined range) of users, programs, or network addresses.
The Nazi blacklist was the list in The Black Book that was drawn up of 2,820 prominent British citizens such as Winston Churchill and Bertrand Russell who would have been sent to concentration camps if the United Kingdom had not won the Battle of Britain and Nazi Germany's Operation Sea Lion had succeeded in conquering Great Britain.
Hollywood anti-communist blacklist
An infamous systematic blacklist was the Hollywood blacklist, instituted by the House Un-American Activities Committee in 1947 to block screenwriters and other Hollywood professionals who were purported to have Communist sympathies from obtaining employment. It started by listing 151 entertainment industry professionals and lasted until 1960 when it was effectively broken by the acknowledgement that blacklisted professionals had been working under assumed names for many years.
California Proposition 8 supporter blacklist
Following the passage of California's Proposition 8, Proposition 8 opponents obtained donation lists of those who had supported the ballot measure by contributing to the "Yes on 8" campaign, published the list, organized an activism group, and began calling for boycotts of the places of work of the supporters to force the firing or resignation of employees. Chad Griffin, a political adviser to Hollywood executives and same-sex marriage supporter explained the intent of the campaign by saying, "Any individual who has held homophobic views and who has gone public by writing a check, you can expect to be publicly judged. Many can expect to pay a price for a long time to come." There has been controversy as to whether this is appropriate response to the passage of Proposition 8 on the part of those opposed to it.
- Construction industry workers blacklisted for 20 years
- Deacon, Harriet; Phillips, Howard; van Heyningen, Elizabeth, eds. (2004). The Cape Doctor in the Nineteenth Century: A Social History (Clio Medica, 74). Editions Rodipi B.V.
- Clarke, Comer (1961). England Under Hitler: Revealed at Last—The Secret Nazi Plans for the Rape of England (paperback ed.). New York: Ballantine Books.
- Wilkerson, William (1946-07-29). "A Vote For Joe Stalin". The Hollywood Reporter. p. 1.
- Baum, Gary; Daniel Miller (Nov. 30, 2012 (Online Nov. 19, 2012)). "Blacklist: THR Addresses Role After 65 Years". Hollywood Reporter. Retrieved 20 November 2012. Check date values in:
- "Resist the Blacklist". The Ledger. 2008-11-22. Retrieved 2009-12-11.
- Rachel Abramowitz and Tina Daunt (November 23, 2008). "Prop. 8 rifts put industry on edge. Hollywood is at odds over whether to shun supporters of the ban". LA Times. Retrieved 2009-12-11.
- Weinstein, Steve (2008-11-25). "Are We Being Bullies? Debate Rages Over Boycotts". Edge. Retrieved 2008-11-26.
- Lorence, James J. (1999). The Suppression of Salt of the Earth: How Hollywood, Big Labor, and Politicians Blacklisted a Movie in Cold War America. University of New Mexico Press. ISBN 0-8263-2027-9.
|Look up blacklist in Wiktionary, the free dictionary.|
|Wikisource has the text of the 1920 Encyclopedia Americana article Blacklisting.|