If your encyclopedia told you that David Beckham was an 18th-century Chinese goalkeeper, that the Duchess of Cornwall carries the title Her Royal Un-Lowness or that Robbie Williams earns his living by eating pet hamsters in pubs "in and around Stoke", you might consider seeking a second opinion.
Despite its breakneck journey toward becoming a global internet phenomenon, such questions of accuracy have dogged the online encyclopedia Wikipedia, launched five years ago.
Fresh concerns about the ease with which Wikipedia's entries can be manipulated have been raised after US politicians were caught altering their profiles to make them more flattering.
Alarm bells rang last month when newspapers in Massachusetts discovered that the staff of Congressman Marty Meehan had polished his biography by, for instance, deleting his long-abandoned promise to serve only four terms and praising his "fiscally responsible" voting record.
Detective work by Wikipedia found that other offices on Capitol Hill had engaged in skulduggery - not all of them with flattering results, such as the false reference to Oklahoma's Tom Coburn being voted "most annoying senator".
Wikipedia said it was reversing changes to several of the politicians' entries, and by so doing, added to the list of controversies about its veracity.
One of the best known happened in December when the US journalist John Seigenthaler complained that his Wikipedia entry implicated him in the assassination of US President John Kennedy. The decision of a member of the public, Brian Chase, to insert the claim "as a joke" to fool a colleague exposed the flaw at the heart of Wikipedia - its openness.
Unlike a conventional encyclopedia employing full-time editors, Wikipedia accepts entries submitted by anyone. And anyone can edit existing entries, rendering them inaccurate or offensive.
Wikipedia believes that this constant editing of an entry will lead to its ultimate perfection. Others see it as a process ripe for misinformation and they do not hold back in their disparagement.
Robert McHenry, a former editor-in-chief of Encyclopaedia Britannica, said: "My thesis has been that, contrary to the Wikipedia idea of constant improvement, it is far more likely that on average bad articles will get better, good ones will get worse, and the mass tend to the mediocre. There are no standards of writing or research. At any given time one can easily find articles that are so badly written as to be unintelligible, while others are quite good. Some that are rife with error, while others seem authoritative.
"The problem for the ordinary user is that it is often not possible to distinguish the one sort from the other."
In the very spirit of openness that provides such ammunition for the snipers, Wikipedia freely admits its weakness. In its own entry, the encyclopedia states that there has been "controversy over its reliability" and lists its perceived problems as "systematic bias, difficulty of fact checking, use of dubious sources, exposure to vandals, privacy concerns, quality concerns, fanatics and special interests, and censorship".
But it also points to its strengths, principal among them the sheer, extraordinary mass of information - some 3.3 million entries - available to the public totally free. It is available in more than 100 languages, and thousands of new entries are added every day.
Wikipedia is one of the biggest experiments in the web's democracy, communality and usefulness, and arguably its most successful exponent of those virtues.
Check on the Battle of Waterloo and find a sober, succinct account of Napoleon's downfall, explore the culinary use of chrysanthemums or delve into the early life of the Babyshambles' singer Pete Doherty. Even the non-league club Burton Albion is honoured with a 702-word history, including its current manager, the name and capacity of its stadium and its home and away strip.
Such global dominance was built from unpromising beginnings. Wikipedia (wiki wiki means "quick" in Hawaiian) was founded in January 2001 as a sideline to the Numedia encyclopedia being written by experts for an American company, Bomis. Under its chief executive, Jimmy Wales, Bomis ran a search engine that included links to pornographic sites and also for a time sold erotic photographs of women.
Mr Wales, an options trader born in Alabama, spent $100,000 (£60,000) of Bomis's money developing Wikipedia before creating a not-for-profit organisation to run the burgeoning encyclopedia. The Wikipedia Foundation is funded by public donations and has just three employees, a lead software developer, Mr Wales's assistant and an intern. But an army of between 600 and 1,000 unpaid administrators, developers, stewards and bureaucrats maintain the site. A bigger pool of 13,000 regular contributors edits at least five entries a month each. Such checking leads to a daily battle of wits with the cyber-wreckers who insert erroneous, ludicrous and offensive material into entries.
How frequently entries get messed about with depends on their subjects. The entry "Muslim" is currently being attacked dozens of times a day in the continuing row about cartoons of the Prophet Mohamed, with angry denunciations of suicide bombing and claims of hypocrisy.
Tony Blair's entry is a favourite for distortion with new statements casting aspersions on his integrity. One concluded a list of his various jobs such as First Lord of the Treasury with the line "and most of all George Bush's Bitch Boy".
Despite the constant battle to mainntain the probity of entries about controversial subjects, studies attest to Wikipedia's accuracy. Nature reported in December that Wikipedia was about as reliable on science subjects as the Encyclopaedia Britannica. Nature found on average that Wikipedia had four inaccuracies per entry compared with three for its more conventional rival. The magazine noted: "Only eight serious errors, such as misinterpretations of important concepts, were detected in the pairs of articles reviewed, four from each encyclopedia." In an evaluation of 66 articles, a German computer magazine, c't, rated Wikipedia 3.6 out of 5 for accuracy, beating two other online encyclopedias, including Microsoft Encarta (3.1).
But Wikipedia still does not have the sheen of respectability for academics. Antony Beevor, the historian, says: "With Wikipedia's entries, there is a lack of satisfaction, not so much through inaccuracy but there are a lot of vague statements which you cannot really disprove but which you don't think are necessarily helpful."
Definitions of the word "Muslim"
* Controversy over the Muslim reaction to cartoons of the Prophet Mohamed, first published in a Danish magazine, is reflected on Wikipedia. Yesterday, the entry "Muslim" was changed 12 times. Over the past week, it was changed more than 50 times. Almost half of the changes were reverting to previous articles after distorted and insulting remarks were made about Muslims. Yesterday, these ranged from the puerile: "The Muslims god [sic] is Farad Muhammad born Wallace Fard," to suggestions which are deliberately offensive. One of these entries suggested that a Muslim is "an adherent of Islam, or blows up innocent civilians by the means of suicide bombing". Wikipedia, which constantly checks that changes improve rather than insult, reverted to the previous entry in less than a minute.
The Russian Revolution, 1917
"The entry on the Russian Revolution reads like the work of a second-rate undergraduate student. It raises an issue because Wikipedia is used by a lot of people as a basic source of information, but this is bland, simplistic and misleading. To say the Russian Revolution was "a political movement" is an odd statement; it was a series of movements and chaotic social disturbances. Wikipedia states "Widespread inflation and famine" contributed to the famine, which is misleading. Russia was a fast-growing but new industrial power. There was no widespread famine between 1914 and 1917 in Russia; the food supply problems were not because of food production. Russia was exporting vast amounts of food. To say "peasants still resented paying redemption payments to noble landowners" is inaccurate, they made the payments to the state. Their goal was not to secure "ownership of the land" but the desire for communal tender of the land. Peasants had freedom of movement, whereas this piece suggests that Russia was stagnant and feudal. It is a simplistic account." - Orlando Figes, professor of history at Birkbeck College, University of London
Kate Moss, model
"Factually, this is dead accurate, though it is cloaked in po-faced language. You can read into it that she is fabulous and successful, or that she is a bisexual, formerly drug-taking, not-very-bright model. But while the account of Moss is factually accurate, it does not mention that she never gives interviews and has never been known to purposefully utter a word in public, and would lose every bit of mystique if she did. It also does not give the context - that bad girls are extremely popular and it can pay off in the 21st century. She is a lousy role model but a great model." - Marcel D'Argy Smith, former editor of 'Cosmopolitan' magazine
Ann Widdecombe, politician and writer
"I think overall that the entry is much better than Dod's parliamentary guide. But the sentence explaining why I went to a convent in Bath, saying that my 'rather strict parents wanted to ensure that [I] received a good education in a virtuous and sex-free environment', is a ludicrous over-interpretation. They were not particularly strict, but wanted me to get a good education in a single-sex school - 'sex-free' did not come into it.
The references to the 2001 leadership election are categorically wrong. Wikipedia says: 'She supported the unsuccessful leadership campaign of Ken Clarke, and afterwards refused to serve in a [Iain] Duncan Smith cabinet', whereas at the start of the leadership campaign, on a Hackney housing estate, I said that I did not have the support to run for leader and simultaneously said that I would be retiring from the front bench. It was not determined on Mr Duncan Smith winning, but was announced well in advance. The entry is pretty good though, I would give them 9.5 out of 10." - Ann Widdecombe
Tony Blair, Prime Minister
"The changes that are made to Wikipedia briefly, and then reverted, such as 'Blair is gay', are puerile and very silly. That is the problem with Wikipedia - most of it is very good and reliable, but it depends on people interested in a subject being able to pontificate.
Being pedantic, Mr Blair is not the youngest prime minister since William Pitt the Younger. Lord Liverpool, who became prime minister in 1824, was younger.
The statement, 'He has deployed British armed forces into four conflicts, in Kosovo, Sierra Leone, Afghanistan and Iraq, also a record for a Labour leader, despite Blair being a devout Christian', is comment. It is opinionated and written from an anti-war point of view, with statements such as, 'What many perceive to be an illegal and immoral invasion of Iraq in 2003' and, 'Blair has shifted justification for the invasion away from WMD'. There were more reasons to go to war than the weapons of mass destruction. Also, Mr Blair never publicly said, 'He would serve only two terms in office'. It is speculated that he hinted privately to Gordon Brown that there would be only two terms.
There are always arguments about biased articles in traditional encyclopedias, but I treat Wikipedia with circumspection, and would check it against a more reliable source." - John Rentoul, biographer of Tony Blair
In vitro fertilisation
"I have always been dubious about Wikipedia, so was interested to review one or two entries. I was surprised by the excellent section 'In vitro fertilisation'. It gives a precise, accurate overview of the state of this technology and most of the newer developments in the field.
This would undoubtedly serve as a useful introduction for those with little idea about the subject; this entry would actually be more useful to the average inquirer with its links than would anything in the Encyclopedia Britannica.
Checking the entry on the British 'House of Parliament' gave further evidence of the Wikipedia's accuracy and focus on relevant points of information. Of The Independent, Wikipedia says: 'While it apparently tries to genuinely represent contrasting political opinions, its politics are probably closest to those of Liberal Democrats.'
And finally I immodestly visited an entry on myself and was disconcerted how it is mostly accurate and very up-to-date. Though I expected to be dismissive of Wikipedia, I am considerably impressed with the quality of information - definitely a useful resource and a reasonable way of getting information about topics one might want to research in more detail." - Robert Winston, fertility expert and television presenter
Philip Larkin, poet
"A good and fair account. It sounds approving of Larkin, which is nice, but it is overall a dispassionate account, as one would expect from a dictionary. The reference to Coventry as a 'provincial city in the English Midlands' is hilarious, but probably necessary for American readers. The piece does not sound that American overall. The reference to Larkin's personal life, 'He never married, preferring to share his life with a number of women - Monica Jones, Maeve Brennan and Betty Mackereth' implies a settledness to the relationships. Larkin did not quite share his life, but that is a matter of interpretation. The way Larkin's reputation is described after Philip Larkin: A Writer's Life was published [by Motion] is fair. There was a huge rumpus when the book came out, but the reputation of the books has survived undimmed. People are canny about separating life and work. It notes Martin Amis's dismissal of the revelations - I disagree with Amis, not with Wiki. Technically, Wikipedia should refer to 'Larkin's literary executor, Anthony Thwaite' as 'one of Larkin's literary executors'. Though I can see there is an opportunity to whitewash with Wikipedia, the few times I have used it, I have been impressed with it." - Andrew Motion, Poet Laureate
"Accurate, but with an odd conglomeration of facts without a clear idea of what purpose Radio 1 serves or who listens to it. The odd mixture of facts does not tell you about the wider picture. It reads a little like a 15-year-old's media essay; it is all there, but cobbled together, probably from various pieces on the internet, without any analysis. To use more than half the entry with current Radio 1 listings is, again, odd, but I like the use of changing logos at the bottom of the entry. You would learn more about Radio 1 if there was a link to all the old jingles from 1967 onwards, than from this particular entry. If you were really interested, you would follow the links from the page, and as an introduction, this is just about passable." - Simon Garfield, author of 'The Nation's Favourite: The True Adventures of Radio 1'
"I am impressed by the amount of information on punting; the two key books on punting are mentioned, as are the clubs. When Wikipedia states, 'Racing is normally done in narrow punts that are only 1ft (30 cm) or 2ft (60 cm) in beam', the reference to 1ft is too narrow; the narrowest punt is 1ft 3 inches. The reason given for racing punters to stand in the middle of the punt, 'Because it is faster to turn round at the end of each leg of a race by stopping the punt and punting back in the other direction instead of attempting to turn round the whole punt', is slightly bizarre. It is the tradition and no one would consider turning their punt around. But this is not a general subject, a lot has been put into this piece and it has been thought out. I am impressed. It works on the presumption that by and large people will correct things, and I changed one small thing on my own biography." - Sandy Nairne, director of the National Portrait Gallery