Shadow banning

Shadow banning (also called stealth banning, ghost banning or comment ghosting) is the act of or partially blocking a user or their content from an  such that it will not be readily apparent to the user that they have been banned.

By partly concealing, or making a user's contributions invisible or less prominent to other members of the service, the hope may be that in the absence of reactions to their comments, the problematic or otherwise out-of-favour user will become bored or frustrated and leave the site, and that spammers and trolls will not create new accounts.

Notable examples
In the mid-1980s, BBS forums including had a "twit bit" for problematic users. When enabled, the user would have limited access, and commonly still be able to read public discussions; however, any messages posted by that "twit" would not be shown to the other users of that group.

Michael Pryor of described stealth banning for online forums in 2006, saying how such a system was in place in the project management system, "to solve the problem of how do you get the person to go away and leave you alone". As well as preventing problem users from engaging in s, the system also discouraged s, who if they returned to the site would be under the false impression that their spam was still in place.  describes it as "one of the oldest moderation tricks in the book", noting that early versions of had a global ignore list known as "Tachy goes to Coventry", as in the British expression "", meaning to ignore them and pretend they don't exist.

A 2012 update to introduced a system of "hellbanning" for spamming and abusive behavior.

has also been known to "ghost" a user's individual ads, whereby the poster gets a confirmation email and may view the ad in their account, but the ad fails to show up in the appropriate category page.

Early on, implemented a similar feature, initially designed to address spam accounts, though it is also used for general users. In 2015, Reddit added an account suspension feature, though the site still makes extensive use of shadow banning.

was found in 2016 to ban posts and messages that contain certain keywords without notice.

In a study that looked at tweets from 2014 to early 2015, over a quarter million tweets were found during the one-year period in Turkey to have been censored via shadow banning. was also found, in 2015, to shadowban tweets containing leaked documents in the US.

The phenomenon was noticed on in 2017; there, certain posts have been seen to be unavailable to people who do not follow one in hashtag searches.

"Shadow banning" became popularized in 2018 as a conspiracy theory that Twitter had shadow-banned Republicans. In late July 2018,  found that several supporters of the no longer appeared in the auto-populated drop-down search menu on Twitter, thus limiting their visibility when being searched for; Vice News alleged that this was a case of shadow-banning. After the story, some conservatives accused Twitter of enacting a shadowban on Republican accounts, which Twitter flatly denied. However, some accounts that were not overtly political or conservative apparently had the same algorithm applied to them. Numerous news outlets, including The New York Times, The Guardian, Buzzfeed News, Engadget and New York magazine, disputed the Vice News story. In a blog post, Twitter said that the use of the phrase "shadow banning" was inaccurate, as the tweets were still visible by navigating to the home page of the relevant account. Later, Twitter appeared to have adjusted its platform to no longer limit the visibility of some accounts.