Plagiarism is taking the ideas of another and using them without giving proper credit. It is a form of stealing and a serious academic offense.
Plagiarism is not necessarily the same as copyright infringement, which occurs when one violates copyright law by failing to get permission from the copyright holder. A violation of the terms of Free Document License can be plagiarism when a proper historical trail of contributions is not present as a reference or a hyperlink in an article.
Plagiarism is unethical behavior that can generate various forms of social punishment such as loss of reputation, failure in a course at a school, loss of a professional job, recall of a book, or forfeiture of a license.
Plagiarism is the passing off of another person's work as one's own. The key is that a person claims credit or appears to claim credit for writing done by someone else. Accidental plagiarism is usually the result of poor citation or referencing, poor preparation, or a misunderstanding of plagiarism. Deliberate plagiarism is an attempt to claim another person's work as one's own, usually by removing telltale evidence so the plagiarism is hard to spot.
An unacknowledged use of words, ideas, information, research, or findings not one's own, taken from any source is plagiarism only if a person is claiming personal credit for originality. It is not plagiarism to use well-known facts without acknowledging a source because readers understand the author is not claiming originality.
According to Diana Hacker, "Three acts are plagiarism: (1) failing to cite quotations and borrowed ideas, (2) failing to enclose borrowed language in quotation marks and (3) failing to put summaries and paraphrases in your own words."  Other experts say that absence of quotation marks is not by itself plagiarism. If they have been removed to hide plagiarism, that proves the plagiarism is deliberate. For other interpretations see MLA (Modern Language Association), the APA (American Psychological Association), Chicago Manual of Style.
Self-plagiarism is the act of copying one's published or submitted writing without mentioning the previous publication. For example, in academic assignments, the submission of the same paper in more than one course is considered self-plagiarism. Self-plagiarism is not usually considered an academic offense, but the deceit involved in submitting the same material for credit in different courses is considered unethical. It is common for scholars to rephrase and republish their own work, as they are constantly developing their ideas.
Excuses used for plagiarism
Intentional plagiarism where an entire essay or research paper is copied from another source is blamed on a combination of stress and laziness. Unintentional plagiarism is blamed on a lack of knowledge about how to cite sources. Plagiarism is so easy to do that many students may not even realize that they might be guilty of plagiarism. Another reason sometimes blamed for plagiarism is cryptomnesia, recalling of memories without realizing their source and thinking these memories are original creations. Helen Keller claimed to have been a victim of cryptomnesia when she wrote "The Frost King".
Frequency of plagiarism
There is no definitive research into the frequency of plagiarism. Any research that has taken place has focused on universities. There are no published statistics for the school or college sectors; awarding bodies do not maintain statistics on plagiarism.
Of the forms of cheating (including plagiarism, inventing data and cheating during an exam), students admit to plagiarism more than any other. Twenty five percent to 90 percent of students admit to plagiarism. However, this figure reduces considerably when students are asked about the frequency of "serious" plagiarism, such as copying most of an assignment or purchasing a complete paper from a website. In those instances only 20 percent and 10 percent report as having plagiarized at that level.
In academic circles, plagiarism is avoided by using a citation style, such as MLA style, Chicago style, or APA style. Generally speaking, facts that are common knowledge, for example the date that WWII ended, need not be referenced; while facts that are not considered common knowledge in one's field must be cited. Similarly, a quote from any source, words or information, even if paraphrased, or any ideas not one's own must be cited.
For instance, while it is acceptable to copy several paragraphs of text from a book and place them in a paper, if the source of the text (the author's name and title of the work) is not identified, even if the text is well known, for example an excerpt from Lewis Carroll's Jabberwocky, it is considered plagiarism.
Similarly, it is considered plagiarism to take someone's idea and then present it as one's own work. However, it is not considered plagiarism when two (or more) people independently come up with the same ideas. This can be the result of simultaneous inspiration, which happens when many people exposed to the same source and some interpret it similarly. This also can happen with short logical phrases that are easily put together by many people independently.
There is some difference of opinion over how much credit must be given in non-academic settings, such as when preparing a newspaper article or historical account. Generally, reference is made to original source material as much as possible, and writers avoid taking credit for others' work. The use of facts in non-academic settings, rather than works of creative expression, does not usually constitute plagiarism.
Commercial plagiarism and anti-plagiarism services
A market has emerged for pre-written papers, often via websites offering essays and papers for sale to students. Some sites provide free documents because they receive monetary support from sponsors. Other websites offer essays for money. These websites provide a database of topics or custom-made essays on any topic for a fee. Some websites offer monthly subscriptions while others offer a price per essay. Generally, such sites include a copyright statement or anti-plagiarism notice with their papers.
Similarly, a counter-industry has developed, with companies offering services for schools and instructors to compare a student's papers to a database of sources and search for plagiarism.
Plagiarism and the Internet
The Internet has provided increased opportunities for plagiarism, since people are now able to use search engines to find information, which can be easily copied and pasted into documents. The Internet can also be used to combat plagiarism. Teachers use search engines for parts of suspicious essays. However, search engine checks offer only a partial solution to spotting plagiarism. The best solution would be to check against a continuously growing body of text. This prevents students from turning in work that may not have been published on the Internet but is otherwise plagiarized.
Many teachers have turned to plagiarism prevention services that automate the search by comparing each paper against millions of online sources. In the early 2000s, many students in Canadian colleges and universities publicly protested against online plagiarism-preventing services, claiming that the use of such services reduced the personal involvement of the instructor with the student's work, introduced the possibility of incorrectly-cited quotations being considered as plagiarized text and, most importantly, assumed a priori guilt on the part of the student(s) in question.
Plagiarism and the law
Plagiarism by students can result in punishment ranging from a failing grade on the particular assignment or course, suspension, or expulsion. Professional academics found guilty of plagiarism can ruin an academic career, result in revocation of one's degree or license, or the loss of one's job.
Although plagiarism is often referred to as "theft" or "stealing," it is not usually prosecuted under criminal law. Sometimes acts that constitute plagiarism are treated as copyright infringement, unfair competition, or a violation of the doctrine of moral rights. More often charges of plagiarism are resolved through disciplinary proceedings.
Just as there can be plagiarism without lawbreaking, it is possible to violate copyright law without plagiarizing. For example, one could distribute the full text of a bestseller on the Internet while giving credit for it to the original author, financially damaging the author and publisher.
In common law countries, plagiarism itself is not a crime; there are copyright infringement laws, and those laws are primarily in the civil codes; criminal codes require that it is both willful and noticeable amounts of money or physical property are involved..
According to some academic ethics codes, a complaint of plagiarism may be initiated or proven by any person. The person originating the complaint need not be the owner of the plagiarized content, nor need there be communication from a content owner directing that an investigation or disciplinary be conducted. In many academic settings intent does not even enter into consideration. Princeton dismisses intent as "irrelevant" and Doug Johnson says that intent is "not necessary for a work to be considered plagiaristic and as one respondent put it, 'ignorance of the law is no excuse.' Some universities will even revoke a degree if plagiarism is proved
Famous examples and accusations of plagiarism
- A young Helen Keller was accused in 1892 for plagiarizing "The Frost King," a short story that strongly resembled Margaret T. Canby's story "The Frost Fairies." She was brought before a tribunal of the Perkins Institute for the Blind, where she was acquitted by a single vote. She "remained paranoid about plagiarism ever after."  
- The 1922 film Nosferatu was an unauthorized adaptation of Bram Stoker's novel Dracula. Stoker's widow sued the producers of Nosferatu, and had many of the film's copies destroyed (although some yet remain).
- George Harrison was successfully sued in a prolonged suit that began in 1971 for plagiarizing the Chiffons' "He's So Fine" for the melody of his own "My Sweet Lord." 
- Atari's video game Pong was accused by Magnavox of being a copy of the Odyssey's tennis game. Nolan Bushnell saw Ralph Baer's version at a 1972 electronics show in Burlingame, California. Bushnell then founded Atari and established Pong as its featured game. "Baer and Magnavox filed suit against Bushnell and Atari in 1973 and finally reached an out-of-court settlement in 1976. It marked the end for Odyssey and the beginning of the Atari age."  
- Alex Haley settled a lawsuit with Harold Courlander for $650,000 in 1978 for a passage in Haley's novel Roots that imitated his novel The African. “Accusations that portions of Roots were plagiarized or concocted plagued Mr. Haley from soon after the book's publication up until his death in February 1992.”
- According to a Boston University investigation into academic misconduct, Martin Luther King, Jr. plagiarized portions of his doctoral thesis that summarizes the concepts of God expressed by Paul Tillich and Henry Nelson Wieman. "A committee of scholars at Boston University concluded yesterday that Rev. Martin Luther King Jr. plagiarized portions of his doctoral dissertation, completed there in the 1950s." Despite the plagiarism, the BU committee recommended that King's doctoral degree should not be revoked. 
- James A. Mackay, a Scottish historian, was forced to withdraw all copies of his biography of Alexander Graham Bell from circulation in 1998 because he plagiarized the last major work on the subject, a 1973 work. Also accused of plagiarizing material on biographies of Mary Queen of Scots, Andrew Carnegie, and Sir William Wallace, he was forced to withdraw his next work, on John Paul Jones, in 1999 for an identical reason.  
- Psychology professor René Diekstra author of popular books, left Leiden University in 1997 after accusations of plagiarism.
- Historian Stephen Ambrose has been criticized for incorporating passages from the works of other authors into many of his books. He was first accused in 2002 by two writers for copying portions about World War II bomber pilots from Thomas Childers's The Wings of Morning in his book The Wild Blue. After admitting to the errors, the New York Times found further unattributed passages, and "Mr. Ambrose again acknowledged his errors and promised to correct them in later editions." 
- Jayson Blair, then a reporter for the New York Times, plagiarized many articles and faked quotes in stories, including the Jessica Lynch and Beltway sniper attacks cases. He and several editors from the Times resigned in June 2003.
New Jersey high-school student Blair Hornstine had her admission to Harvard University revoked in July 2003 after she was found to have passed off speeches and writings by famous figures, including Bill Clinton, as her own in articles she wrote as a student journalist for a local newspaper.
- Long-time Baltimore Sun columnist Michael Olesker resigned on January 4, 2006, after being accused of plagiarizing other journalists' articles in his columns.
- The doctoral thesis written by Kimberly Lanegran at the University of Florida was copied nearly verbatim by Marks Chabedi and submitted at The New School. When Lanegran discovered this, she launched an investigation into Chabedi and he was fired from a professorship at University of the Witwatersrand in South Africa, and The New School revoked his Ph.D. A retraction was issued by a scholarly journal that published an article Chabedi plagiarized 
- Science fiction author Harlan Ellison sued and won in a case against James Cameron, claiming that his film The Terminator plagiarized the two episodes he wrote for the television show The Outer Limits: "Soldier" and "Demon with a Glass Hand".
- Doris Kearns Goodwin, 2002 scandal.
- Writer and television commentator Monica Crowley was accused of plagiarism for a 1999 Slate Magazine article on Richard Nixon.
- Numerous passages of Robert Mason's 1983 Vietnam War memoir Chickenhawk were copied, almost word-for-word, by Charles Sasser and Ron Alexander in their 2001 book, Taking Fire.
- Conservative blogger Ben Domenech, soon after he was hired to write a blog for the Washington Post in 2006, was found to have plagiarized a number of columns and articles he'd written for his college newspaper and National Review Online, lifting passages from a variety of sources ranging from well-known pundits to amateur film critics. After initially blaming any wrongdoing on past editors, Domenech eventually resigned and apologized.
- Dan Brown, author of The Da Vinci Code, has been twice accused of plagiarism resulting in lawsuits, but both suits were ultimately dismissed. Brown was accused of "appropriating the architecture" of the 1978 novel Holy Blood, Holy Grail by Michael Baigent and Richard Leigh. A British judge dismissed the copyright infringement claim in April 2006. The publicity brought Holy Blood, Holy Grail back to the bestseller list. Additionally, Brown was accused by novelist Lewis Perdue for plagiarizing his novels The Da Vinci Legacy (1983) and Daughter of God (2000). A U.S. judge dismissed that case in August 2005.
- Kaavya Viswanathan, a Harvard University student and novelist, whose first novel was How Opal Mehta Got Kissed, Got Wild and Got a Life (2006), is reported to contain plagiarized passages from at least five other novels. Her publisher, Little, Brown and Co. subsequently withdrew all editions of the book and rescinded her publishing deal.
- ↑ http://www.bedfordstmartins.com/book.asp?1149000255 A Pocket Style Manual, 4th ed., 2004 Bedford/St. Martin's, pp 228-30
- ↑ Stuart Green, http://faculty.law.lsu.edu/stuartgreen/pdf/j-green2.pdf
- ↑ http://www.copyright.gov/title17/92chap5.html#506
- ↑ http://www.rbs2.com/plag.htm#anchor777777.
- ↑ Walter Kendrick, “Her Hands Were a Bridge to the World” (New York Times, August 30, 1998).
- ↑ Helen Keller, The Story of My Life, 1903, http://www.afb.org/MyLife/book.asp?ch=P1Ch14
- ↑ http://abbeyrd.best.vwh.net/mysweet.htm
- ↑ "A 30 Year Odyssey for Home Video Games," Chicago Sun-Times, February 16, 2003
- ↑ http://www.pong-story.com/odyssey.htm
- ↑ Esther B. Fein, "Book Notes," New York Times, March 3, 1993.
- ↑ Charles A. Radin, "Panel Confirms Plagiarism by King at BU," Boston Globe, October 11, 1991.
- ↑ Ralph Blumenthal, "Repeat Accusations of Plagiarism Taint Prolific Biographer," New York Times, September 21, 1999.
- ↑ Ralph Blumenthal, "Familiarity Stops the Presses," New York Times, September 26, 1999.
- ↑ David D. Kirkpatrick, "2 Say Stephen Ambrose, Popular Historian, Copied Passages," New York Times, January 5, 2002.
- ↑ David D. Kirkpatrick, "As Historian's Fame Grows, So Do Questions on Methods," New York Times, January 11, 2002 (http://select.nytimes.com/gst/abstract.html?res=F60916FB355D0C728DDDA80894DA404482)
- ↑ Kim Lanegran's account of this incident was published in the Chronicle of Higher Education http://chronicle.com/free/v50/i43/43c00101.htm .
- ↑ http://taylorandfrancis.metapress.com/index/HGCMLCCAEXHRU9M7.pdf For those who wish to look up the actual dissertations in Dissertation Abstracts Online, the OCLC number for Lanegran's dissertation is AAG9801108 and the OCLC number for Chabedi's "dissertation" is AAI9980001.
- ↑ Doris Kearns Goodwin, Liar: First she plagiarized. Then she claimed it wasn't plagiarism.] by Timothy Noah, Slate Magazine, Jan. 2002 http://www.slate.com/id/2061056/
- ↑ Timothy Noah, "Historians Rewrite History," Nov. 2003, http://slate.msn.com/id/2091197/
- ↑ How the Goodwin Story Developed, History News Network, http://hnn.us/articles/590.html
- ↑ http://www.slate.com/id/1003470/
- What is the price of plagiarism? A The Christian Science Monitor article. Retrieved April 12, 2007.
- The Assessment in Higher Education web site's plagiarism page contains links to a variety of resources (articles, books, cheat sites, etc) on plagiarism. Retrieved April 12, 2007.
- A new scholarly journal on the topic is "Plagiary: Cross-disciplinary Studies in Plagiarism, Fabrication, and Falsification." http://www.plagiary.org/ Retrieved April 12, 2007.
- How to Avoid Plagiarism and How to get better essays while reducing your work and plagiarism. Retrieved April 12, 2007.
- Plagiarism FAQ. Retrieved April 12, 2007.
- A massive list of songs that have been plagiarized from another groups' song or sound very similar - this page is in German, but is mostly a large table of songs that can easily be read by English speakers. Retrieved April 12, 2007.
- The Responsible Plagiarist: Students Who Misuse Sources (PDF). Retrieved April 12, 2007.
- Indiana University at Bloomington: Understanding Plagiarism
- KOPI Online Plagiarism Search and Information Portal. Retrieved April 12, 2007.
- copycat82, the case-study, on a Ph.D. plagiarism, in the USA. Retrieved April 12, 2007.
- Educational Fair Use Guidelines observed March 17, 2007.
- Kentucky Labrary Association. Retrieved April 12, 2007.
- Online Plagiarism Checker Compares text with text that exists on the Internet
- EVE2 (Essay Verification Engine 2.4)
- Moss (a Measure Of Software Similarity), a free online service to investigate source code plagiarism. MossPlus is the commercial version.
- Plagiarism Checker, a free detector for teachers and authors
- Plagiarism Search, A free search engine promoting academic integrity.
- Firefox Plagiarism Plugin, A plagiarism search engine plugin for Firefox.
- The Essay Inspector is a web-based collusion detection application.
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