So in elementary school, I was told not to use Wikipedia too much because you can't trust what they write. So then for all the projects, I used the Canadian Encyclopedia, but then now, I really would like to know why not to use Wikipedia. The only answer I know of is that anyone can write anything, but doesn't it have to go through a review under someone that actually is part of the Wikipedia community? What I think, is that Wikipedia takes a lot of information from other websites, then puts it all together, which is why normally, they have a big bibliography. I was wondering- Is Wikipedia really trustworthy?
Wikipedia is a crowd-sourced site where anybody can contribute, just like this one. Wikipedia strives for verifiability and neutrality and has an active user community, but that doesn't mean that things can't get past it. It doesn't mean information there can't be wrong. Some pages are full of detailed, reliable information; some are not. So, in evaluating the reliability of what you read on any given page there -- or anywhere else! -- you need to ask yourself how they know what they say.
Do they cite sources? Good Wikipedia pages do. Do they not cite sources but make a logical argument? (Not so common on Wikipedia, but common elsewhere on the Internet, including Stack Exchange.) Do they present evidence?
Since you asked about Wikipedia I'll focus on sources. For a first approximation, ask yourself if the sources cited are generally considered to be credible. If they cite peer-reviewed, publicly-available research, that's pretty good. If they cite the National Enquirer (a tabloid full of sensationalist fiction masquerading as news), be very suspicious. If the facts you're checking are particularly important, central to your thesis for example, then you might need to actually go look up some of those sources to confirm that the Wikipedia page accurately represents them. If the facts are less important or tangential, or your assignment doesn't call for this degree of rigor, then establishing that Wikipedia's sources are credible might suffice without looking them up.
For Wikipedia in particular, you can also check the "talk" page associated with the topic you're looking at. The "talk" pages can sometimes tell you if any content is disputed or of questionable quality. If the "talk" page is empty, though, don't assume that means everything's fine -- it might mean that no experts have looked at the topic yet.
It's impossible to say, globally, "Wikipedia is trustworthy" or "Wikipedia is not trustworthy". Unlike an edited, curated encyclopedia, it contains material at a range of quality levels. I find Wikipedia to be a good starting point in research; sometimes I find everything I need there (including supporting sources), and sometimes I don't. Don't rule it out, but do be prepared to go beyond it.
Things changed. Several reviews on the reliability of Wikipedia concluded it is about as accurate as more standard encyclopaedias, while having more content. I too have heard that Wikipedia should not be used at all when I was in school, but nowadays, at least at the universities I have some acquaintances in, professors do not hesitate to point to Wikipedia when they consider an article is pertinent and of quality. Thus, fears about the collaborative nature of Wikipedia being a major source of unreliability now are seemingly fading away: on the contrary, it leads to more content, with an approximately equal degree of accuracy as others encyclopaedias.
That said, Wikipedia, as well as other encyclopaedias, should never be used as references. This is because of the intrinsic nature of an encyclopaedia, which produces inherent limitations.
An encyclopaedia is meant as a compilation of the current knowledge. How is it done? By using reliable sources of information. As such, an encyclopaedia never produces new information, it only summarizes what was already done by others. In addition, to increase reliability and ensure notability of inclusion, only secondary sources (eg, journalists articles) can be used, rarely primary sources (the original source: a book, an interview, a talk, etc). An encyclopaedia is itself a tertiary source (so you can see we are getting further and further from the original information...).
This leads us to solve a common misconception, and the probable reason why encyclopaedia are frowned upon as sources for any serious work: they can only ensure verifiability, not the truth.
Indeed, since encyclopaedias can only compile knowledge, never create it, they are often limited to the current common knowledge, and not the state of the art. In addition, the usage of secondary sources might (heavily) bias the content included: a notable falsity cited by lots of reliable journals will be included whereas a truth only published in a book will not be notable enough to be included. Both of these inherent flaws are most apparent in fast moving information domains, such as articles on political events or figures, as well as contemporary history.
To take a somewhat extreme illustration, a poll on the french Wikipedia asked "whether, if Wikipedia existed a few centuries ago, it would state that the Sun revolved around the Earth". The majority (84%) answered yes.
In the end, Wikipedia, as well as any other encyclopaedia, can be a great first low-ceiling entry to a new knowledge you want to get, but it can only be seen as a gate to dive deeper into the included references, as well as the non-included references that you can find by your own means, which is particularly important if you are looking for the state-of-the-art (instead of only the current common knowledge).
I like to say that broadly speaking, Wikipedia is mostly trustworthy when statements are cited, but it's never a source.
There are several parts to this.
Wikipedia is broadly and mostly trustworthy -- Most of the time, especially in articles of broad interest, errors are caught and at least flagged, if perhaps not addressed, quickly. This is what the  notice is about for claims that aren't obviously unreasonable. (Claims that are obviously unreasonable are likely to just be deleted outright. A claim that "US president candidate Hillary Clinton was born on the planet Jupiter" is more likely to be deleted outright than flagged as "citation needed", for example. Extraordinary claims require extraordinary evidence and all that.)
When statements are cited -- This is an important caveat. Yes, anyone can write anything on Wikipedia. Good edits come with clear in-line citations. A statement that properly cites its source can be judged based on the source. As Monica Cellio pointed out, not all sources are created equal, so you need to exercise due diligence here. Beware of circular source references where, if you follow the line of citations and sources, you end up back where you started. You can reduce the risk of this by checking the Wikipedia page's revision history to see when a specific claim was added or cited to a source, and compare that to the publication or edit history of the cited source. The Internet Archive's Wayback Machine can also be useful here.
But it's never a source -- This is something a lot of people get wrong. You should never cite Wikipedia in any authoritative manner. Wikipedia, just like any other encyclopedia, is a summarization, and very often a simplification. In fact, Wikipedia prohibits adding material that cannot be verified using external references (they refer to this as verifiability, not truth). If it matters, then go to the source or to a specialist publication, preferably a peer-reviewed one, and cite that one (or better yet, several).
With the above caveats, Wikipedia is generally a good way to get a general overview of a subject. It's a nice starting place to find out what more you might want to read. If a specific fact is important, you should always verify it against some unrelated work anyway whether you start out on Wikipedia or with a printed encyclopedia. (Real scientists verify the results of others all the time, especially with new results that don't match earlier models.) Do note that this places a larger burden on you than simply checking that the sources listed for the claim on Wikipedia support the claim; you want to independently confirm the claim, not just confirm that the claim can be supported by whatever someone said supports the claim.
Let's say you are writing a report on how airplanes can fly; you might go to Wikipedia, or your favorite search engine, and type "how airplanes fly" into the search box. If you do that on Wikipedia, you might end up on the page about airplanes, and from there you might follow the link to its page about aircraft wings, which in turn will tell you that aerodynamic forces are involved, from where you can follow the link to the page on aerodynamics which goes into some of the gory details, including links to separate pages on subjects such as incompressible flows and transonic flows, along with separate pages on different types of engines (air-breathing pure jet engines, propeller engines including piston and turboprop engines, rocket engines, ...). Those pages, if you take the time to read and understand them, will probably give you a pretty decent idea of the details of how airplanes are able to fly, to the point that you could probably write up a pretty good summary yourself of how it all fits together, which (unless you're well into the upper years of the school system) your teacher would likely be happy with. However, it would not be a good idea to try to design an actual aircraft with just those, as they just aren't detailed enough. (It's unlikely that you'd even be able to get a pilot's license to fly aircraft just by studying those. You'd likely miss out on some details that are important in such a context, and spend too much time on things that are relatively unimportant.)
Which brings me to what you wrote in a comment to one of the answers...
So is it a good website to use when doing research for a project?
Research is a somewhat loaded term. It can be used colloquially as in "learn more about something", but it can also be used in the scientific meaning of "gathering data" or "determining what model best fits the available data". Wikipedia is generally nice for the former, but it's absolutely useless for the latter. When you're doing a school project, it's a gradual change from the former to the latter as you move up the educational system; by the time you're in college or university, you'll be expected to be doing more of the latter than the former. That implies that you won't even be going to Wikipedia's sources, at least by way of Wikipedia; you'll be reading relevant scientific publications directly.
In summary, don't be afraid to refer to Wikipedia, but if it's important for what you're doing, always at the very least check the sources. Consider any statement that doesn't cite its sources to be at best dubious.
The idea that anyone can edit Wikipedia is often put forward as a bad thing, but with Wikipedia it's part of the peer review process and this happens a lot faster than it does with printed encyclopedias.
It also depends how you use it - as Monica mentions, the trick is to treat every page as a piece of journalism, and use it as a starting summary for the references cited - as such, it's a valuable introduction to the concept of critical thinking.
At junior school level teachers are more interested in students' abilities to find the relevant information in accepted reference sources. At further and higher education levels, the idea of questioning any reference source becomes more significant. At that point, the reliability of established reference sources (Canadian, Britannica, etc.) will also be called into question. Several studies have been done comparing Wikipedia with established reference sources - a few are listed here (https://en.wikipedia.org/wiki/Reliability_of_Wikipedia), though it's always worth considering the source.
Is it a good place to find information? Yes. Is it a definitive font of all wisdom? No. Will it contain the answers a school teacher wants from their students? Maybe, maybe not - but the text book or other recommended source will.
Wikipedia policy requires that editors cite sources to support their edits. However, there's no systematic process for checking that editors are accurately representing the sources they cite, or that the sources are reliable, or that they even exist.
It usually works pretty well when a page attracts attention from multiple editors who are willing to scrutinise and challenge one another. For instance, if I add something to George W. Bush's Wikipedia page that isn't true, it's very likely that somebody else who has good knowledge of W's life will notice and call me on it. At that point, if I can't produce an acceptable source to support my edit, that edit will be reverted, and if I keep trying to push the point I'll probably eventually get banned.
However, there are cases where the Wikipedia model doesn't work so well. A couple of examples:
(1) Wikipedia policy leans heavily on the notion of "reliable sources", which is inherently difficult to define - in some cases the same newspaper/etc. may be reliable on certain topics and unreliable on others.
As an example, a friend of mine edited the Wiki article on one of her favourite entertainers, adding a "fact" about him which she'd just made up. It was plausible and innocuous, but utterly fictional. She didn't include a citation for this "fact", but nobody challenged it at the time, because it wasn't the kind of page that attracts close scrutiny.
A couple of years later, two major newspapers wrote profiles of this guy. Both of them used information from the Wikipedia article including my friend's "fact" without mentioning that they'd taken it from Wikipedia, and apparently without checking it.
Both of these papers would generally be considered "reliable sources" by Wiki's standards - one is among the world's most prestigious newspapers - and the Wikipedia article now cites both of them as evidence for the "fact". If you google his name, my friend's fake "fact" now appears at the top of the search results.
(No, I'm not going to give more details; it's not harming anybody and it's a useful reminder that even newspapers of record get lazy with fact-checking sometimes.)
(2) Wikipedia editors vastly prefer online sources for reasons of convenience. A source that's not available online is much less likely to be checked, and this can be exploited. Back when I was editing Wikipedia I found one bad-faith editor who was making up cites to sources that simply didn't exist, because it was much easier for him to make things up than it was for other editors to go track down an off-line source available in only one location to check whether it really said what he claimed.
As others have suggested, it's generally a bad idea to cite Wikipedia directly, but it can be a very good place to start: read the Wikipedia article, check what sources it cites, and then go look up those sources... and check whether the Wikipedia article has represented them accurately.
Wikipedia is not a reliable source. Wikipedia can be edited by anyone at any time. This means that any information it contains at any particular time could be vandalism. Biographies of living persons are especially vulnerable to this issue. Some of the article information might not be accurately true, which is therefore considered to be wrong.
Wikipedia generally uses reliable secondary sources, which vet data from primary sources. If the information on another Wikipedia page (which you want to cite as the source) has a primary or secondary source, you should be able to cite that primary or secondary source and eliminate the middleman (or "middle-page" in this case).
Always be careful of what you read: it may not be consistently reliable.
If you're relying on Wikipedia as a source, then it's worth noting that the Wikipedia page on identifying reliable sources for use in Wikipedia articles states in no uncertain terms that Wikipedia articles (and Wikipedia mirrors) in themselves are not reliable sources for any purpose.
That's not as paradoxical as it sounds, because a Wikipedia article should countain references to sources, and it's those sources you should be able to rely on, not the article itself. However, if you dig a little deeper you'll find that wikipedia guidelines encourage the use of secondary sources and strongly discourage the use of primary sources, though in practice these guidelines aren't always followed. This policy was formulated for logical reasons, but depending on how you look at it you may think this makes Wikipedia more or less reliable.
It heavily depends on the topic.
If it's about mathematics, computer science, physics, then Wikipedia is very trustworthy.
If it's an article about politics, ideology, history, or any topic large masses of people hold as an important self-identification criteria, then don't touch it even with a very long stick, as the group which happens to have more activists, dominates the article by being able to post more citations proving their side, and reverting edits made by others. Even if all citations come from reputable sources (which cannot be always guaranteed), an article can be biased by, for example, by having an excessively long section dedicated to criticism in case of an article about a person or group, where such could have been summarized in a short paragraph.
Wikipedia is a great place to start your research, but not to complete it. All good Wikipedia pages include cited reputable sources, so the best advice is to use Wikipedia to identify primary sources, and then use those instead for your final paper.
In general, while Wikipedia's average reliability may be equal to a standard reference work, that reliability varies greatly by page. (It also varies over the course of time, which a stable reference typically does not.) A good rule of thumb is that the more popular and the less controversial a page is, the more reliable. Less popular pages are not reviewed or edited often, so wrong, biased or outdated info can persist there a long time. And more controversial pages can be subject to "edit wars," carefully constructed misinformation, and or unintentionally slanted coverage.
A big part of the reason is that a Wikipedia page is constantly changing, so the way to effectively cite it isn't obvious; but Wikipedia is a much deeper system than it appears.
Wikipedia articles include an edit history, which is a clear tracking of every change made to a page. A proper citation include what date the material was accessed and therefore which version it refers to. Also, the "talk" page allows for any discussion about choices made, so you can follow the discussion which lead to some specific solutions.
In a nutshell:
Wikipedia values citation and notability over accuracy and direct knowledge from the source.
Pick your favorite book, movie, etc. Let's say the main character is a man from Asia. If were to go on air and state that the main character is a female alien from Pluto then wikipedia would use that as a source and edit accordingly. Let that sink in.
I know it a prevalent issue because I posed the question no less then at least 10 times over the period of a few months in their editor help chat to see whether I was misunderstanding their policies (which appear to encourage such behavior). Several people would get irritated when I said we shouldnt use the news article. Their response was that it is a reputable institution and therefore refusing to yse the article makes them look bad. Of course, that is editors opinions but it still shows the general trend.
So definitely take wikipedia with a grain of salt. If some famous reputable scientist posts a quack paper and it gets used on wikipedia it will take months to edit it out. People literally have massive arguments over the title of a page or whether some wording is ambiguous.
Now consider an encyclopedia run by people knowledgeable in a particular subject and building just that one section and critically deciding what is and isnt true. That is the difference in quality.
Plus, wikipedia is built as a general overview for notability purposes, not science or mathematics. So do not expect to find formal proofs of notable theorems or demonstrations of scientific experiments. Expect to primarily find why the item is important and how it is relevant to the everyday person.
Very late, but here's a couple of points:
Read Wikipedia's own warnings. Banners at the top will say things like "lacks sufficient sources" or "has peacock writing". These are flags that something is not right.
Check the talk page. If there's edit warring going on, approach the current revision with a grain of salt.
Look at the amount and quality of sources. If there are a lot of sources that are of decent quality (i.e., no tabloids, or other such nonsense) you're probably good to go.
Check the grammar. If it's sloppily written, that's a bad sign - an editor hasn't gotten around to it to clean up.
If the article passes all these checks, it is very likely that it's good to go. See for example the article cited by another answerer - these good articles are just as good as those in a normal encyclopedia.
Let me next address your questions about peer review. Currently, an experiment at Wikipedia means that there are some restrictions on who can create articles, and all new articles (both those created as drafts by new users and those created directly on the site) are reviewed, though there are currently backlogs.
Edit: As of a few weeks ago this has been put permanently in place. All unregistered users cannot create new articles and must do so as drafts.
Returning to your regularly scheduled
As for edits, tons of users constantly scan for vandalism - a lot of the most egregious stuff is reverted almost instantly. Not every edit is individually reviewed, necessarily, but I'd guess that due to the level of effort put toward vandalism patrol, quite a few are. Further, since there are WikiProjects and tons of users who simply love a subject, articles are frequently read and checked by experts and enthusiasts.
I might recommend checking out Wikipedia for yourself - by which I mean, try editing Wikipedia. Create an account, learn the policies. See how it all ticks. I did, and have enjoyed it (and also learned a lot about both Wikipedia and all sorts of interesting subjects) and it has certainly increased my awareness of how good the info I get from Wikipedia is, and how to judge when it isn't good.
Hope this helps!
My opinion is for neutral subjects it can be largely trusted but for controversial topics like politics, religion and disputes it can be used as reading material but take it with a pinch of salt. For example you can trust article on Betelgeuse or Black hole but not much an article on Jesus or Hitler.
If you search a little bit, you will find article after article dealing with this question, especially in the academic sphere. There is a long list of criticism of Wikipedia.
Some of it goes back to it nature, such as the fact that it is a crowd-sourced site. Some of it goes back to its policies, e.g. its open denial of expert knowledge or its stance on deletism. And some of it goes back to its practices, such as closed administrator circles or the running of the foundation.
So in essence, many different people have many different reasons to be somewhere between cautious and critically opposed to Wikipedia, and in considering all of their arguments and their respective validities, one has to admit that at least some of the criticism is most likely true and important enough to not rely on Wikipedia as a source.
That does not mean you cannot use Wikipedia at all, but it should be one of your sources, not the only or the primary one. Some schools or universities have a strict policy of not using Wikipedia as a source at all, but even that does not mean you cannot go to Wikipedia to get a quick overview of a topic and find links to primary and secondary sources there, which you then can use and cite.
Wikipedia is a great place to start research, as it can point to other references.
Don't use it as a source.
Before reading, choose to remain open-minded about its truthfulness.
Here are some reasons why:
- Because of careless writers and the fact that anyone can edit, even honest Wikipedia citations can't always be trusted
- Because of demographic issues among editors, there is probably a hyper-strong bias toward white males
Note: Wikipedia is probably almost as accurate as other encyclopedias, especially in STEM subjects. Remember:
- Politically-charged topics—unlike mathematically proofs—often result in biased articles.
- Writers of traditional encyclopedias are probably biased, too.
- Wikipedia is useful because it has a huge base of knowledge, is quickly added upon, and quickly edited. Traditional encyclopedias are slow to update.
No information source is entirely trustworthy. But for purposes of citation, we need to distinguish three kinds of information: evidence, interpretation, and reporting.
Evidence is the original data.
Interpretation is what something thinks the original data, or a collection of data means.
Reporting is someone else passing on the interpretation, perhaps in different language suitable to a different audience.
Wikipedia is, by its charter, 100% reporting.
With reporting, there is always the issue of bias. That is, the person doing the reporting may have an axe to grind and may therefore not report honestly or accurately. They may twist the original evidence or interpretation to suit their own ends.
In the early days of the web, where no one really understood what was happening online, it was assumed that the work of professional writers and scholars working for a publishing house must be more honest reporting than the work of anonymous strangers on the internet. Some people still feel this way. But we now understand how social proof and participatory editing work and it seems that while the process is very different, the effect is just as reliable (and far more complete) than that of the professional publishing houses.
Thus Wikipedia is largely rehabilitated as a source of reporting. Obviously, as with other sources of reporting, not every article it contains is equally trustworthy. You always have to do a degree of due diligence, particularly on articles that may not get much attention and therefore don't have the mechanisms of social proof going for them.
We should also note that neither social proof or academic and commercial blessing mean that reporting is always accurate. Societies always live a lie to one extent or another. There are always conclusions that may be completely true which are outlawed by the cohesive lie of the society in which they are reported. In short, there are some things you are not allowed to say no matter how true they may be. There are not societies in which this is not true of something.
For scholarly purposes, however, you have to make a distinction between when it is appropriate to cite research, interpretation, and reporting. All three may be acceptable for different purposes, but for anything that touches the heart of the argument you are making, citing reporting is unacceptable. You have to report interpretation or evidence, ideally evidence. This is not a critique of Wikipedia. It is simply about maintaining the ability to trace the assertions in an argument back to their source, and citing reporting is not consistent with that aim.
tl;nr; Wikipedia is far from perfect, but a statement "don't use wikipedia" is quite extreme. When somebody has interest to falsify an article, it's not trustworthy. Otherwise it normally is.
Wikipedia has mechanisms to verify content - lots of articles cite information sources, some articles are protected and only certain people can edit them, etc. Before trusting the article you need to check whether the source really states what the article says (I have seen sources which are completely bogus). It is not required that an article passes review after being modified, but there are users who do that on selected articles (or just on random recent changes). Article "vandalism" is usually caught quickly.
You can ask yourself whether somebody has an interest to falsify a given article. Without ever having read them, I'd suppose articles like Alligator or Computer keyboard are quite trustworthy. On the other hand, I wouldn't really trust Catalan independence or Monsanto (at least not for everything).
The fact is, there are paid editors on wikipedia. I have some personal experience with that.
Several years ago there were discussions about the Trans-Pacific Partnership and I noticed several people were putting lots of effort to remove the word "controversial" from the first paragraph. When there are such disagreements, people make discussions, but nobody was really giving arguments why the word shouldn't be there (it came from two trustworthy sources). Somebody repeatedly removed the word stating as reasons things like "We decided to remove it in the discussion" while there was nothing like that in the discussion. This was obviously a paid editor.
I decided to monitor the article and several days later new attempts to remove the word started from different accounts. The problem is that wikipedia has a rule that you cannot revert more than 3 times in a day and I was the only person trying to stop the editors. After making 4 reverts, I got reported by one of the paid editors (Phoenix7777). I tried explaining the situation to several people (including administrators), but nobody responded.