Anonymous social media is a subcategory of social media wherein the main social function is to share and interact around content and information anonymously on mobile and web-based platforms. Another key aspect of anonymous social media is that content or information posted is not connected with particular online identities or profiles. == Background == Appearing very early on the web as mostly anonymous-confession websites, this genre of social media has evolved into various types and formats of anonymous self-expression. One of the earliest anonymous social media forums was 2channel, which was first introduced online on May 30, 1999, as a Japanese text board forum. With the way digital content is consumed and created continuously changing, the trending shift from web to mobile applications is also affecting anonymous social media. This can be seen as anonymous blogging, or various other format based content platforms such as nameless question and answer online platforms like Ask.fm introduced mobile versions of their services. The number of new networks joining the anonymous social sharing scene continues to grow rapidly. == Degrees of anonymity == Across different forms of anonymous social media there are varying degrees of anonymity. Some applications, such as Librex, require users to sign up for an account, even though their profile is not linked to their posts. While these applications remain anonymous, some of these sites can sync up with the user's contact list or location to develop a context within the social community and help personalize the user's experience, such as Yik Yak or Secret. Other sites, such as 4chan and 2channel, allow for a purer form of anonymity as users are not required to create an account, and posts default to the username of "Anonymous". While users can still be traced through their IP address, there are anonymizing services like I2P or various proxy server services that encrypt a user's identity online by running it through different routers. Secret users must provide a phone number or email when signing up for the service, and their information is encrypted into their posts. Stylometry poses a risk to the anonymity or pseudonymity of social media users, who may be identifiable by writing style; in turn, they may use adversarial stylometry to resist such identification. == Controversy == Apps such as Formspring, Ask, Sarahah, Whisper, and Secret have elicited discussion around the rising popularity of anonymity apps, including debate and anticipation about this social sharing class. As more and more platforms join the league of anonymous social media, there is growing concern about the ethics and morals of anonymous social networking as cases of cyber-bullying, and personal defamation occurs. Formspring, also known as spring.me, and Ask.fm have both been associated with teen suicides as a result of cyberbullying on the sites. Formspring has been associated with at least three teen suicides and Ask.fm with at least five. For instance, the app Secret got shut down due to its escalated use of cyberbullying. The app Yik Yak has also helped to contribute to more cyberbullying situations and, in turn, was blocked on some school networks. Their privacy policy meant that users could not be identified without a subpoena, search warrant, or court order. Another app called After School also sparked controversy for its app design that lets students post any anonymous content. Due to these multiple controversies, the app has been removed from both Apple and Google app stores. As the number of people using these platforms multiplies, unintended uses of the apps have increased, urging popular networks to enact in-app warnings and prohibit the use for middle and high school students. 70% of teens admit to making an effort to conceal their online behavior from their parents. Even Snapchat has some relation to the health of children after using social media. This is an app that is meant to be quick and simple but in many ways it can be overwhelming. A person can post something, and it will be gone in seconds. Oftentimes, the post that was made was inappropriate and harmful to another person. It's a never-ending cycle. Some of these apps have also been criticized for causing chaos in American schools, such as lockdowns and evacuations. In order to limit the havoc caused, anonymous apps are currently removing all abusive and harmful posts. Apps such as Yik Yak, Secret, and Whisper are removing these posts by outsourcing the job of content supervision to oversea surveillance companies. These companies hire a team of individuals to inspect and remove any harmful or abusive posts. Furthermore, algorithms are also used to detect and remove any abusive posts the individuals may have missed. Another method used by the anonymous app named Cloaq to reduce the number of harmful and abusive posts is to limit the number of users that can register during a certain period. Under this system, all contents are still available to the public, but only registered users can post. Other websites such as YouTube have gone on to create new policies regarding anonymity. YouTube now does not allow anonymous comments on videos. Users must have a Google account to like, dislike, comment or reply to comments on videos. Once a sign-in user "likes" a video, it will be added to that user's 'Liked video playlist'. YouTube changed their "Liked video playlist" policy in December 2019, allowing a signed-in user to keep their "Liked video playlist" private. Historically, these controversies and the rise of cyberbullying have been blamed on the anonymous aspect of many social media platforms, but about half of US adult online harassment cases do not involve anonymity, and researchers have found that if targeted harassment exists offline it will also be found online, because online harassment is a reflection of existing prejudices. == As platforms for anonymous discussion == Anonymous social media can be used for political discussion in countries where political opinions opposed to the government are normally suppressed, and allow persons of different genders to communicate freely in cultures where such communication is not generally accepted. In the United States, the 2016 presidential election led to an increase in the use of anonymous social media websites to express political stances. Moreover, anonymous social media can also provide authentic connection to complete anonymous communication. There have been cases where these anonymous platforms have saved individuals from life-threatening situation or spread news about a social cause. Additionally, anonymous social websites also allow internet users to communicate while also safeguarding personal information from criminal actors and corporations that sell users' data. A study in 2017 on the content posted to 4chan's /pol/ board found that the majority of the content was unique, including 70% of the 1 million images included in the studied data set. == Revenue generated by anonymous social media == === Anonymous apps === Generating revenue from anonymous apps has been a discussion for investors. Since little information is collected about the users, it is difficult for anonymous apps to advertise to users. However some apps, such as Whisper, have found a method to overcome this obstacle. They have developed a "keyword-based" approach, where advertisements are shown to users depending on certain words they type. The app Yik Yak has been able to capitalize on the features they provide. Anonymous apps such a Chrends take the approach of using anonymity to provide freedom of speech. Telephony app Burner has regularly been a top grossing utilities app in the iOS and Android app stores using its phone number generation technology. Despite the success of some anonymous apps, there are also apps, such as Secret, which have yet to find a way to generate revenue. The idea of an anonymous app has also caused mixed opinions within investors. Some investors have invested a large sum of money because they see the potential revenue generated within these apps. Other investors have stayed away from investing these apps because they feel these apps bring more harm than good. === Anonymous sites === There are several sources to generate revenue for anonymous social media sites. One source of revenue is by implementing programs such as a premium membership or a gift-exchanging program. Another source of revenue is by merchandising goods and specific usernames to users. In addition, sites such as FMyLife, have implemented a policy where the anonymous site will receive 50% of profit from apps that makes money off it. In terms of advertisements, some anonymous sites have had troubles implementing or attracting them. There are several reasons for this problem. Anonymous sites, such as 4chan, have received few advertisement offers due to some of the contents it generates. Other anonymous sites, such as Reddit, have been ca
ViBe
ViBe is a background subtraction algorithm which has been presented at the IEEE ICASSP 2009 conference and was refined in later publications. More precisely, it is a software module for extracting background information from moving images. It has been developed by Oliver Barnich and Marc Van Droogenbroeck of the Montefiore Institute, University of Liège, Belgium. ViBe is patented: the patent covers various aspects such as stochastic replacement, spatial diffusion, and non-chronological handling. ViBe is written in the programming language C, and has been implemented on CPU, GPU and FPGA. == Technical description == Source: === Pixel model and classification process === Many advanced techniques are used to provide an estimate of the temporal probability density function (pdf) of a pixel x. ViBe's approach is different, as it imposes the influence of a value in the polychromatic space to be limited to the local neighborhood. In practice, ViBe does not estimate the pdf, but uses a set of previously observed sample values as a pixel model. To classify a value pt(x), it is compared to its closest values among the set of samples. === Model update: Sample values lifespan policy === ViBe ensures a smooth exponentially decaying lifespan for the sample values that constitute the pixel models. This makes ViBe able to successfully deal with concomitant events with a single model of a reasonable size for each pixel. This is achieved by choosing, randomly, which sample to replace when updating a pixel model. Once the sample to be discarded has been chosen, the new value replaces the discarded sample. The pixel model that would result from the update of a given pixel model with a given pixel sample cannot be predicted since the value to be discarded is chosen at random. === Model update: Spatial Consistency === To ensure the spatial consistency of the whole image model and handle practical situations such as small camera movements or slowly evolving background objects, ViBe uses a technique similar to that developed for the updating process in which it chooses at random and update a pixel model in the neighborhood of the current pixel. By denoting NG(x) and p(x) respectively the spatial neighborhood of a pixel x and its value, and assuming that it was decided to update the set of samples of x by inserting p(x), then ViBe also use this value p(x) to update the set of samples of one of the pixels in the neighborhood NG(x), chosen at random. As a result, ViBe is able to produce spatially coherent results directly without the use of any post-processing method. === Model initialization === Although the model could easily recover from any type of initialization, for example by choosing a set of random values, it is convenient to get an accurate background estimate as soon as possible. Ideally a segmentation algorithm would like to be able to segment the video sequences starting from the second frame, the first frame being used to initialize the model. Since no temporal information is available prior to the second frame, ViBe populates the pixel models with values found in the spatial neighborhood of each pixel; more precisely, it initializes the background model with values taken randomly in each pixel neighborhood of the first frame. The background estimate is therefore valid starting from the second frame of a video sequence.
Geofence warrant
A geofence warrant or a reverse location warrant is a search warrant issued by a court to allow law enforcement to search a database to find all active mobile devices within a particular geo-fence area. Courts have granted law enforcement geo-fence warrants to obtain information from databases such as Google's Sensorvault, which collects users' historical geolocation data. Geo-fence warrants are a part of a category of warrants known as reverse search warrants. == History == Geofence warrants were first used in 2016. Google reported that it had received 982 such warrants in 2018, 8,396 in 2019, and 11,554 in 2020. A 2021 transparency report showed that 25% of data requests from law enforcement to Google were geo-fence data requests. Google is the most common recipient of geo-fence warrants and the main provider of such data, although companies including Apple, Snapchat, Lyft, and Uber have also received such warrants. == Legality == === United States === Some lawyers and privacy experts believe reverse search warrants are unconstitutional under the Fourth Amendment to the United States Constitution, which protects people from unreasonable searches and seizures, and requires any search warrants be specific to what and to whom they apply. The Fourth Amendment specifies that warrants may only be issued "upon probable cause, supported by Oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized." Some lawyers, legal scholars, and privacy experts have likened reverse search warrants to general warrants, which were made illegal by the Fourth Amendment. Groups including the Electronic Frontier Foundation have opposed geo-fence warrants in amicus briefs filed in motions to quash such orders to disclose geo-fence data. In 2024, a panel of the United States Fourth Circuit Court of Appeals considered data acquired from Google’s Sensorvault not to be a search, but non-private business records when users opt-in to Google’s location history. However, upon a rehearing en banc, the Court vacated that decision. In April 2025, the full Court affirmed the judgment solely on the 'good faith' exception, leaving the underlying constitutional question of whether geofence warrants constitute a search unsettled in the Circuit. However, the United States Fifth Circuit Court of Appeals found that geofence warrants are "categorically prohibited by the Fourth Amendment." The split in Circuits prompted the United States Supreme Court to agree to hear Chatrie v. United States in January 2026.
Tandem (app)
Tandem is a mobile language exchange and language learning app. == History == Tandem was founded in Hannover, Germany in 2014 by Arnd Aschentrup, Tobias Dickmeis, and Matthias Kleimann. Prior to founding Tandem, the trio had launched Vive, a members-only mobile video chat platform. Tandem has been criticised for not accepting members into the community immediately, as opposed to competitors including HelloTalk, Speaky or Cafehub. In some countries, there is a waiting list and applicants can wait up to seven days for their application to be processed by human moderators. In 2015, Tandem completed its first funding round (seed funding) of €600,000. Participating investors included business angels such as Atlantic Labs (Christophe Maire), Hannover Beteiligungsfonds, Marcus Englert (Chairman of the Supervisory Board of Rocket Internet SE ), Catagonia, Ludwig zu Salm, Florian Langenscheidt, Heiko Hubertz, Martin Sinner, and Zehden Enterprises. In 2016, the company received a further €2 million from new investors Rubylight and Faber Ventures, as well as from existing investors Hannover Beteiligungsfonds, Atlantic Labs, and Zehden Enterprises. Since 2018, the premium membership Tandem Pro has been available, which offers members unlimited access to all language learning features of the app as well as the removal of advertising for a monthly fee.
Lost Art-Database
The Lost Art-Datenbank is an online database published by the German Lost Art Foundation (Deutsches Zentrum Kulturgutverluste. It contains information on cultural objects looted from Jewish collectors or transferred due to Nazi persecution during the Nazi era. Until 2015, it was managed by the Koordinierungsstelle für Kulturgutverluste (Magdeburg Coordination Office). == Creation == Following the Washington Conference of 1998, and the commitments to provide more transparency regarding looted art, Germany launched the Lost Art Database in 2000 order to help Holocaust victims and their families track down artworks that had been looted from them or lost due to Nazi persecution. == Functionality == The Lost Art Database lists art and books and other cultural objects that were lost, seized, stolen or forceably sold during the Nazi era. The database is divided into search requests from victims' families, heirs or institutions and "found" reports from cultural institutions on items with unresolved provenance gaps from the Nazi periods. The section on reports of finds lists objects that are known to have been unlawfully seized or relocated as a result of the war. In addition, reports are published here on cultural objects for which an uncertain or incomplete provenance may indicate a possible unlawful seizure or war-related relocation. The publication of reports in the Lost Art Internet Database is carried out on behalf of and with the consent of the reporting persons and institutions. The responsibility for the content of the reports lies with these legal or natural persons. There have been controversies over which items should be included in the database. Lost Art is based on the Washington Principles adopted in 1998, which Germany has committed itself to implementing (Joint Declaration, 1999). The Lost Art Database is considered a key resource in the search for looted art and the victims of persecution. Every item in the Lost Art Database has an identifier, known as a Lost Art ID. Proveana is the linked research database. == Other lost art databases == Other countries have launched databases to help identify Nazi looted art. Each database has its own area of focus. The German Lost Art Database allows families or heirs to submit information. Other countries have databases that focus on looted artworks that have not been found or artworks that were repatriated to the national authorities after the defeat of the Nazis but were never returned to their original owners. Other databases have been created for stolen antiquities, looted art from colonial era, art stolen from Syria, Iraq, Ukraine, or from museums or collectors.
Principle of rationality
The principle of rationality (or rationality principle) was coined by Karl R. Popper in his Harvard Lecture of 1963, and published in his book Myth of Framework. It is related to what he called the 'logic of the situation' in an Economica article of 1944/1945, published later in his book The Poverty of Historicism. According to Popper's rationality principle, agents act in the most adequate way according to the objective situation. It is an idealized conception of human behavior which he used to drive his model of situational analysis. Cognitive scientist Allen Newell elaborated on the principle in his account of knowledge level modeling. == Popper == Popper called for social science to be grounded in what he called situational analysis or situational logic. This requires building models of social situations which include individual actors and their relationship to social institutions, e.g. markets, legal codes, bureaucracies, etc. These models attribute certain aims and information to the actors. This forms the 'logic of the situation', the result of reconstructing meticulously all circumstances of an historical event. The 'principle of rationality' is the assumption that people are instrumental in trying to reach their goals, and this is what drives the model. Popper believed that this model could be continuously refined to approach the objective truth. Popper called his principle of rationality nearly empty (a technical term meaning without empirical content) and strictly speaking false, but nonetheless tremendously useful. These remarks earned him a lot of criticism because seemingly he had swerved from his famous Logic of Scientific Discovery. Among the many philosophers having discussed Popper's principle of rationality from the 1960s up to now are Noretta Koertge, R. Nadeau, Viktor J. Vanberg, Hans Albert, E. Matzner, Ian C. Jarvie, Mark A. Notturno, John Wettersten, Ian C. Böhm. == Newell == In the context of knowledge-based systems, Newell (in 1982) proposed the following principle of rationality: "If an agent has knowledge that one of its actions will lead to one of its goals, then the agent will select that action." This principle is employed by agents at the knowledge level to move closer to a desired goal. An important philosophical difference between Newell and Popper is that Newell argued that the knowledge level is real in the sense that it exists in nature and is not made up. This allowed Newell to treat the rationality principle as a way of understanding nature and avoid the problems Popper ran into by treating knowledge as non physical and therefore non empirical.
WebGPU Shading Language
WebGPU Shading Language (WGSL, internet media type: text/wgsl) is a high-level shading language and the normative shader language for the WebGPU API on the web. WGSL's syntax is influenced by Rust and is designed with strong static validation, explicit resource binding, and portability in mind for secure execution in browsers. In web contexts, WebGPU implementations accept WGSL source and perform compilation to platform-specific intermediate forms (for example, to SPIR‑V, DXIL, or MSL via the user agent), but such backends are not exposed to web content. == History and background == Graphics on the web historically used WebGL, with shaders written in GLSL ES. As applications demanded more modern GPU features and finer control over compute and graphics pipelines, the W3C's GPU for the Web Community Group and Working Group created WebGPU and its companion shading language, WGSL, to provide a secure, portable model suitable for the web platform. WGSL was developed to be human-readable, avoid undefined behavior common in legacy shading languages, and align closely with WebGPU's resource and validation model. == Design goals == WGSL's design emphasizes: Safety and determinism suitable for web security constraints (extensive static validation and well-defined semantics). Portability across diverse GPU backends via an abstract resource model shared with WebGPU. Readability and explicitness (no preprocessor, minimal implicit conversions, explicit address spaces and bindings). Alignment with modern GPU features (compute, storage buffers, textures, atomics) while retaining a familiar C/Rust-like syntax. == Language overview == === Types and values === Core scalar types include bool, i32, u32, and f32. Vectors (e.g., vec2, vec3, vec4) and matrices (up to 4×4) are available for floating-point element types. Optional f16 (half precision) may be enabled via a WebGPU feature; availability is implementation-dependent. Atomic types (atomic