User-generated content (UGC), alternatively known as user-created content (UCC), is any form of content created by users of a system or service and made available publicly on that system. UGC most often appears as supplements to online platforms, such as social media websites, and may include such content types as blog posts, wikis, videos, or comments.
The term "user-generated content" and concept it refers to entered mainstream usage in the mid-2000s, having arisen in web publishing and new media content production circles. The BBC adopted a user-generated content platform for its websites in 2005, and TIME Magazine named "You" as the Person of the Year in 2006, referring to the rise in the production of UGC on Web 2.0 platforms.
User-generated content is used for a wide range of applications, including problem processing, news, entertainment, advertising, gossip and research. It is an example of the democratization of content production; whereas during the 1970s and 1980s, traditional "gatekeepers" such as newspaper editors, publishers and news shows approved all content and information before it was aired or published, in the 1990s and 2000s, as media production through new technologies has become more accessible, user friendly and affordable to the general public, large numbers of individuals are able to post text, digital photos and digital videos online, with little or no "gatekeepers" or filters.
The advent of user-generated content marked a shift among media organizations from creating online content to providing facilities for amateurs to publish their own content. User-generated content has also been characterized as Citizen Media as opposed to the 'Packaged Goods Media' of the past century. Citizen Media is audience-generated feedback and news coverage. People give their reviews and share stories in the form of user-generated and user-uploaded audio and user-generated video. The former is a two-way process in contrast to the one-way distribution of the latter. Conversational or two-way media is a key characteristic of so-called Web 2.0 which encourages the publishing of one's own content and commenting on other people's.
The role of the passive audience therefore has shifted since the birth of New Media, and an ever-growing number of participatory users are taking advantage of the interactive opportunities, especially on the Internet to create independent content. Grassroots experimentation then generated an innovation in sounds, artists, techniques and associations with audiences which then are being used in mainstream media. The active, participatory and creative audience is prevailing today with relatively accessible media, tools and applications, and its culture is in turn affecting mass media corporations and global audiences.
It is important to have an objective before attempting to become part of the UGC/social networking environment. For example, companies may ask users to post their reviews directly to their Facebook page. This could end up disastrous if a user makes a comment that steers people away from the product.
Mere copy & paste or hyperlinking could also be seen as user-generated self-expression. The action of linking to a work or copying a work could in itself motivate the creator, express the taste of the person linking or copying. Digg.com, StumbleUpon.com, and leaptag.com are good examples of where such linkage to work happens. The culmination of such linkages could very well identify the tastes of a person in the community and make that person unique.
User-generated content in publications may have started with the letters to the editor columns of eighteenth century newspapers. In the 1990s several electronic bulletin board systems were based on user-generated content. Some of these systems have been converted into websites, including the film information site IMDb which started as rec.arts.movies in 1990. With the growth of the World Wide Web the focus moved to websites, several of which were based on user-generated content, including Wikipedia (2001) and Flickr (2004).
The BBC set up a user generated content team as a pilot in April 2005 with 3 staff. In the wake of the 7 July 2005 London bombings and the Buncefield oil depot fire, the team was made permanent and was expanded, reflecting the arrival in the mainstream of the citizen journalist. After the Buncefield disaster the BBC received over 5,000 photos from viewers. The BBC does not normally pay for content generated by its viewers.
In 2006 CNN launched CNN iReport, a project designed to bring user generated news content to CNN. Its rival Fox News Channel launched its project to bring in user-generated news, similarly titled "uReport". This was typical of major television news organisations in 2005–2006, who realised, particularly in the wake of the London 7 July bombings, that citizen journalism could now become a significant part of broadcast news. Sky News, for example, regularly solicits for photographs and video from its viewers.
User-generated content was featured in Time magazine's 2006 Person of the Year, in which the person of the year was "you", meaning all of the people who contribute to user generated media such as YouTube and Wikipedia. A precursor to user-generated content uploaded on YouTube was America's Funniest Home Videos.
While the benefit derived from user generated content for the content host is clear, the benefit to the contributor is less direct. There are various theories behind the motivation for contributing user generated content, ranging from altruistic, to social, to materialistic. Due to the high value of user generated content, many sites use incentives to encourage their generation. These incentives can be generally categorized into implicit incentives and explicit incentives.
The distribution of UGC across the Web provides a high volume data source that is accessible for analysis, and offers utility in enhancing the experiences of end users. Social science research can benefit from having access to the opinions of a population of users, and use this data to make inferences about their traits. Applications in information technology seek to mine end user data to support and improve machine-based processes, such as information retrieval and recommendation. However, processing the high volumes of data offered by UGC necessitate the ability to automatically sort and filter these data points according to their value. 
Determining the value of user contributions for assessment and ranking can be difficult due to the variation in the quality and structure of this data. The quality and structure of the data provided by UGC is application-dependent, and can include items such as tags, reviews, or comments that may or may not be accompanied by useful metadata. Additionally, the value of this data depends on the specific task for which it will be utilized and the available features of the application domain. Value can ultimately be defined and assessed according to whether the application will provide service to a crowd of humans, a single end user, or a platform designer. 
The variation of data and specificity of value has resulted in various approaches and methods for assessing and ranking UGC. The performance of each method essentially depends on the features and metrics that are available for analysis. Consequently, it is critical to have an understanding of the task objective and its relation to how the data is collected, structured, and represented in order to choose the most appropriate approach to utilizing it. The methods of assessment and ranking can be categorized into two classes: human-centered and machine-centered. Methods emphasizing human-centered utility consider the ranking and assessment problem in terms of the users and their interactions with the system, whereas the machine-centered method considers the problem in terms of machine learning and computation. The various methods of assessment and ranking can be classified into one of four approaches: community-based, user-based, designer-based, and hybrid. 
There are many types of user-generated content: Internet forums, where people talk about different topics; blogs are services where users can post about many topics, product reviews on a supplier website or in social media; wikis such as Wikipedia and Wikia allow users, sometimes including anonymous users, to edit the content. Another type of user-generated content are social networking sites like Facebook, Twitter, Instagram or VK, where users interact with other people chatting, writing messages, or posting images or links. Media hosting sites such as YouTube allow users to post content.
Entertainment media publications include Reddit, 9Gag, 4chan, Upworthy, Inbound.org, and Distractify. Sites like 9Gag allow users to create memes and quick video clips. Sites like Tech in Asia and Buzzfeed engage readers with professional communities by posting articles with user-generated comment sections. Other types of this content are fanfiction like FanFiction.Net, imageboards; various works of art, as with deviantArt and Newgrounds; mobile photos and video sharing sites such as Picasa and Flickr; customer review sites; audio social networks such as SoundCloud; crowd funding, like Kickstarter; or crowdsourcing. Some forms of user-generated content can be considered as a form of citizen journalism.
Video games can have fan-made content in the form of mods, fan patches, fan translations or server emulators. Some games come with level editor programs to aid in their creation. A few massively multiplayer online role-playing games including Star Trek Online and EverQuest 2 have UGC systems integrated into the game itself. A metaverse can be a user-generated world, such as Second Life.
A popular use of UGC involves collaboration between a brand and a user. For example, the "Elf Yourself" videos by Jib Jab that come back every year around Christmas. The Jib Jab website lets people use their photos of friends and family that they have uploaded to make a holiday video to share across the internet. You cut and paste the faces of the people in the pictures to animated dancing elves.
Some bargain hunting websites feature user-generated content, such as Dealsplus, Slickdeals, and FatWallet which allow users to post, discuss, and control which bargains get promoted within the community. Because of the dependency of social interaction, these sites fall into the category of social commerce.
Wikipedia, a free encyclopedia, is one of the largest user-generated content databases in the world.
Photo sharing websites: Flickr is a site in which users are able to upload personal photos they have taken and label them in regards to their "motivation". Flickr not only hosts images but makes them publicly available for reuse and reuse with modification. It is entirely user-generated content.
The incorporation of user-generated content into mainstream journalism outlets is considered to have begun in 2005 with the BBC's creation of a user-generated content team, which was expanded and made permanent in the wake of the July 7, 2005 London bombings. The incorporation of Web 2.0 technologies into news websites allowed user-generated content online to move from more social platforms such as MySpace, LiveJournal, and personal blogs, into the mainstream of online journalism, in the form of comments on news articles written by professional journalists, but also through surveys, content sharing, and other forms of citizen journalism.
Since the mid-2000s, journalists and publishers have had to consider the effects that user-generated content has had on how news gets published, read, and shared. A 2016 study on publisher business models suggests that readers of online news sources value articles written both by professional journalists, as well as users-- provided that those users are experts in a field relevant to the content that they create. In response to this, it is suggested that online news sites must consider themselves not only a source for articles and other types of journalism, but also a platform for engagement and feedback from their communities. The ongoing engagement with a news site that is possible due to the interactive nature of user-generated content is considered a source of sustainable revenue for publishers of online journalism going forward.
The use of user-generated content has been prominent in the efforts of marketing online, especially among millennials. A good reason for this may be that while in the US, 14 percent of consumers trust a brand-made ad, 48 percent of consumers trust UGC. An increasing number of companies have been employing UGC techniques into their marketing efforts, such as Starbucks with their "White Cup Contest" campaign where customers competed to create the best doodle on their cups.
The effectiveness of UGC in marketing has been shown to be significant as well. For instance, the "Share a Coke" by Coca-Cola campaign in which customers uploaded images of themselves with bottles to social media attributed to a two percent increase in revenue. Of millennials, UGC can influence purchase decisions up to fifty-nine percent of the time, and eighty-four percent say that UGC on company websites has at least some influence on what they buy, typically in a positive way. As a whole, consumers place peer recommendations and reviews above those of professionals.
User-generated content used in a marketing context has been known to help brands in numerous ways.
The term "user-generated content" has received some criticism. The criticism to date has addressed issues of fairness, quality, privacy, the sustainable availability of creative work and effort among legal issues namely related to intellectual property rights such as copyrights etc.
Some commentators assert that the term "user" implies an illusory or unproductive distinction between different kinds of "publishers", with the term "users" exclusively used to characterize publishers who operate on a much smaller scale than traditional mass-media outlets or who operate for free. Such classification is said to perpetuate an unfair distinction that some argue is diminishing because of the prevalence and affordability of the means of production and publication. A better response might be to offer optional expressions that better capture the spirit and nature of such work, such as EGC, Entrepreneurial Generated Content (see external reference below).
Sometimes creative works made by individuals are lost because there are limited or no ways to precisely preserve creations when a UGC Web site service closes down. One example of such loss is the closing of the Disney massively multiplayer online game "VMK". VMK, like most games, has items that are traded from user to user. Many of these items are rare within the game. Users are able to use these items to create their own rooms, avatars and pin lanyard. This site shut down at 10 pm CDT on 21 May 2008. There are ways to preserve the essence, if not the entirety of such work through the users copying text and media to applications on their personal computers or recording live action or animated scenes using screen capture software, and then uploading elsewhere. Long before the Web, creative works were simply lost or went out of publication and disappeared from history unless individuals found ways to keep them in personal collections.
Another criticized aspect is the vast array of user-generated product and service reviews that can at times be misleading for consumer on the web. A study conducted at Cornell University found that an estimated 1 to 6 percent of positive user-generated online hotel reviews are fake.
The ability for services to accept user-generated content opens up a number of legal concerns: depending on local laws, the operator of a service may be liable for the actions of its users. In the United States, the "Section 230" exemptions of the Communications Decency Act state that "no provider or user of an interactive computer service shall be treated as the publisher or speaker of any information provided by another information content provider." This clause effectively provides a general immunity for websites that host user-generated content that is defamatory, deceptive or otherwise harmful, even if the operator knows that the third-party content is harmful and refuses to take it down. An exception to this general rule may exist if a website promises to take down the content and then fails to do so.
Copyright laws also play a factor in relation to user-generated content, as users may use such services to upload works—particularly videos—that they do not have the sufficient rights to distribute. In many cases, the use of these materials may be covered by local "fair use" laws, especially if the use of the material submitted is transformative. Local laws also vary on who is liable for any resulting copyright infringements caused by user-generated content; in the United States, the Online Copyright Infringement Liability Limitation Act (OCILLA)—a portion of the Digital Millennium Copyright Act (DMCA), dictates safe harbor provisions for "online service providers" as defined under the act, which grants immunity from secondary liability for the copyright-infringing actions of its users. However, to qualify for the safe harbors, the service must promptly remove access to alleged infringing materials upon the receipt of a notice from a copyright holder or registered agent, and the service provider must not have actual knowledge that their service is being used for infringing activities. The European Union's approach is horizontal by nature, which means that civil and criminal liability issues are addressed under the Electronic Commerce Directive. Section 4 deals with liability of the ISP while conducting "mere conduit" services, caching and web hosting services.
A study from York University in Ontario in 2012 conducted a research that resulted in a proposed framework for comparing brand-related UGC and to understand how the strategy used by a company could influence the brand sentiment across different social media channels. A study by Dhar and Chang, published in 2007, found that the volume of blogs posted on a music album was positively correlated with future sales of that album.
Content from Wikipedia