A wiki is a hypertext publication housing a digital knowledge base, which typically facilitates collaborative editing as it allows the public or specific members of an organization to create and modify pages for their audience, though pages can be restricted and users can be blocked.

The internet houses an endless number of wikis, as they're easy to make, so most people typically choose to provide a short list of notable or relevant wikis. You can find attempts at a near-comprehensive lists, but WikiStats only covers MediaWiki forks, some of which have shut down, and the Wiki Wiki is held back by the number of editors in addition to Fandom/Wikia's so-called 'spam' filter on forked wikis.

Regardless of its scale or scope, a wiki's merit and trustworthiness isn't something you can simply infer from search results, requiring you to ask around to see the flaws. Typically, the flaws range from administrative interference (e.g. personal biases, headcanons), lack of quality editors, to the fact that the average person just has better things to do than 'fix' a wiki or 'debate' in a talk page.

Encyclopedia Dramatica (ED) was an internet drama wiki that once focused on LiveJournal drama in 2004,²⁾ but deviated to overdone shock humor,³⁾ then it shuttered after the controversial 'return to form' attempt in 2011.⁴⁾⁵⁾⁶⁾ Historically, it was once praised for its wealth of internet culture,⁷⁾⁸⁾ but these 'merits' has since been taken away by Know Your Meme or the Soyjak Wiki, and much of its content is stuck in the 2000s.

The psychological impact of the wiki onto its contributors and readers can't be understated, masking cases of cyberstalking as trolling, and fueling self-hatred in social rejects to foster extremist ideologies. In fact, their past administrators include a neo-Nazi of Jewish descent⁹⁾ and a 2017 school shooter,¹⁰⁾ while the content has led to a 2018 van attack¹¹⁾ and a 2022 nightclub shooting.¹²⁾¹³⁾

Fandom, previously known as Wikia, is a wiki hosting service that was founded by a for-profit company in 2004 and sold to TPG Capital in 2018.¹⁴⁾ The service is heavily discouraged for its bloated layouts and excessive advertisements, most notable on mobile devices,¹⁵⁾ then came the 'entertainment' acquisitions,¹⁶⁾¹⁷⁾ deals with the U.S. Navy¹⁸⁾ and McDonalds (see Grimace Shake incident), and the AI crap.¹⁹⁾

Many wikis have attempted to migrate away, but Fandom would be aggressive towards dissent (e.g. puppet regimes,²⁰⁾ spam filters,²¹⁾ SEO weaponization²²⁾, etc.), justifiying a need for the Anti-Wikia Alliance, Indie Wiki Federation, and extensions like Indie Wiki Buddy. With the Minecraft Wiki's exit, the addition of more advertiser-friendly policies,²³⁾ and internal downsizing,²⁴⁾ there's been a surge.

Know Your Meme (KYM) is a wiki for memes and viral phenomenon, founded in 2007, and it had ended up becoming mainstream in 2011.²⁵⁾²⁶⁾ The wiki has sullied the definition of a 'meme', which were essentially 'secret online in-jokes',²⁷⁾ but removing the 'secret' and 'in-joke' components have crafted this odd 'rapid humor' ecosystem that sources their relatively bland mainstream humor from Reddit, TikTok, Twitter, etc.

In addition, the wiki relies on a restrictive 'editorship' system for every single page which severely limits the number of people allowed to edit certain articles, some galleries are just stolen softcore pornography,²⁸⁾ political biases tend to shine in certain articles (e.g. GamerGate, Poljak), and some of their articles ironically omit or lack critical information that it was supposedly designed to combat.

“I am grateful to be here today to testify about the potential for the Wikipedia model of collaboration and information sharing which may be helpful to government operations and homeland security.”
– Jimmy Wales²⁹⁾

“Wikipedia is forced to tell a “winner's history”, which can only be based on whatever information actually made it to a reliable source. Reliable sources do not always reflect the truth.”
– Shii³⁰⁾

Wikipedia is a popular and massive wiki that was co-founded by libertarian entrepreneurs in 2001, and has been managed by the nonprofit Wikimedia Foundation since 2003. The wiki is rather infamous for their aggressive donation drives, which occurs every other day³¹⁾ and all of December, though they arguably don't need it^32)33)34)35) as they have enough money to last 20 years,³⁶⁾ on top of the benefactors!³⁷⁾

Despite its neutrality policy, Wikipedia will uncritically parrot false information from 'verifiable' sources, occasionally falls into the trap of argumentum ad populum or confirmation bias, and so on. You should never hail it as this 'infallible arbitrator of truth', when it's typically 'the news' with extra steps,³⁸⁾ and you really shouldn't develop or get your politics from here.³⁹⁾⁴⁰⁾

Beyond this, it's just general nitpicking and pettiness in the community. I understand that some things aren't notable enough to warrant an article,⁴¹⁾ but what is 'not useful for readers', why does it come up in several discussions, and who gets to decide that? You also have these editors who hound pages that are supposedly too long, like it's their job to keep Wikipedia under 32 GB or so. It's just all really silly.

• The term 'wiki' stems from WikiWikiWeb, the first user-editable wiki, borrowing the Hawaiian word 'wiki' (lit. “fast”, “quick”) after the founder recalled the Wiki Wiki Shuttle.

• Personal wiki - A subset of wikis that are solely maintained by a single person.

• Wiki on Wikipedia
• List of Wikis on Compendium of Personal Ignorance