Twitch is a live streaming video platform owned by Twitch Interactive, a subsidiary of Amazon.com.  Introduced in June 2011 as a spin-off of the general-interest streaming platform, Justin.tv, the site primarily focuses on video game live streaming, including broadcasts of eSports competitions, in addition to creative content, " real life " streams, and more recently, music broadcasts. Content on the site can either be viewed live or via video on demand.
The popularity of Twitch would eclipse that of its general-interest counterpart; in October 2013, the website had 45 million unique viewers, :38 and by February 2014, it was considered the fourth largest source of peak Internet traffic in the United States. At the same time, Justin.tv's parent company was re-branded as Twitch Interactive to represent the shift in focus – Justin.tv was shut down in August 2014. That month, the service was acquired by Amazon for $ 970 million, which later led to the introduction of synergies with the company's subscription service Amazon Prime. Twitch later acquired Curse, an operator of online video gaming communities, and introduced means to purchase games through links on streams, along with a program allowing streamers to receive commissions on the sales of games that they play.
In 2015, Twitch announced it had more than 1.5 million broadcasters and 100 million visitors per month. As of Q3 2017, Twitch still remains to be the leading live streaming video service for video games in the US, and has superior advantages comparing to YouTube Gaming.  
When Justin.tv was launched in 2007 by Justin Kan and Emmett Shear, the site was divided into several content categories. The gaming category grew especially fast, and became the most popular content on the site. In June 2011, :40 the company decided to spin off the gaming content as Twitch.TV, inspired by the term twitch gameplay. It launched officially in public beta on June 6, 2011.  Since then, Twitch has attracted more than 35 million unique visitors a month. Twitch had about 80 employees in June 2013,  which increased to 100 by December 2013. The company was headquartered in San Francisco's Financial District.
Twitch has been supported by significant investments of venture capital, with US$15 million in 2012 (on top of US$7 million originally raised for Justin.tv),   and US$20 million in 2013.  Investors during three rounds of fund raising leading up to the end of 2013 included Draper Associates, Bessemer Venture Partners and Thrive Capital. :40 In addition to the influx of venture funding, it was believed in 2013 that the company had become profitable. :40
Especially since the shutdown of its direct competitor Own3d.tv in early 2013, Twitch has become the most popular e-sports streaming service by a large margin, leading some to conclude that the website has a "near monopoly on the market".  Competing video services, such as YouTube and Dailymotion, began to increase the prominence of their gaming content to compete, but have had a much smaller impact so far.   As of mid-2013, there were over 43 million viewers on Twitch monthly, with the average viewer watching an hour and a half a day.  As of February 2014, Twitch is the fourth largest source of Internet traffic during peak times in the United States, behind Netflix, Google, and Apple. Twitch makes up 1.8% of total US Internet traffic during peak periods. 
Growth, acquisition speculation
On February 10, 2014, Twitch's parent company Justin.tv, Inc. was renamed Twitch Interactive, reflecting the increased prominence of the service over Justin.tv as the company's main business.  That same month, a stream known as Twitch Plays Pokémon, a crowdsourced attempt to play Pokémon Red using a system translating chat commands into game controls, went viral; by February 17, the channel had reached over 6.5 million total views since its introduction five days prior, and was averaging concurrent viewership between 60 and 70 thousand viewers, with at least 10% participating. Vice President of Marketing Matthew DiPietro praised the stream, considering it "one more example of how video games have become a platform for entertainment and creativity that extends WAY beyond the original intent of the game creator. By merging a video game, live video and a participatory experience, the broadcaster has created an entertainment hybrid custom made for the Twitch community. This is a wonderful proof of concept that we hope to see more of in the future."   Beginning with its 2014 edition, Twitch was made the official live streaming platform of the Electronic Entertainment Expo. 
August 2014 changes
On August 5, 2014, the original Justin.tv site was abruptly shut down, citing a need to focus resources entirely on Twitch.  On August 6, 2014, Twitch introduced an updated archive system, with multi-platform access to highlights from past broadcasts by a channel, higher quality video, increased server backups, and a new Video Manager interface for managing past broadcasts and compiling "highlights" from broadcasts that can also be exported to YouTube. Due to technological limitations and resource requirements, the new system contained several regressions; the option to archive complete broadcasts on an indefinite basis ("save forever") was removed, meaning that they can only be retained for a maximum of 14 days, or 60 for partners and Turbo subscribers. While compiled highlights can be archived indefinitely, they were limited to two hours in length.   Additionally, all on-demand videos became subject to acoustic fingerprinting using software provided by Audible Magic; if copyrighted music (particularly, songs played by users from outside of the game they are playing) is detected, the 30-minute portion of the video which contains the music will be muted. Live broadcasts are not subject to these filters.  
The audio filtering system, along with the lack of communication surrounding the changes in general, proved to be controversial among users. In particular, users felt that the new filtering system was too inaccurate, flagged music played within games themselves, and voiced concerns that it could affect the service's ability to present footage from games which notably include large amounts of licensed music, such as the Grand Theft Auto series. The change also drew comparisons to the similar policies employed by YouTube —especially given the rumors surrounding Google's bid to purchase the service. In a Reddit AMA, co-founder Emmett Shear admitted that his staff had "screwed up" and should have provided advance warning of the changes, and promised that Twitch had "absolutely no intention" of implementing audio filtering on live broadcasts.  On August 7, 2014, the 2-hour length limit on highlights was again removed, and an appeals process was added for flagged audio contained within on-demand recordings. In January 2015, to further rectify these issues, Twitch introduced a royalty-free music library featuring tracks from various independent labels cleared for use in streams. 
Amazon.com subsidiary (2014–present)
On August 25, 2014, it was announced that Amazon.com would acquire Twitch Interactive for US$970 million. The deal was expected to be finalized by the end of 2014.   Sources reported that the rumored Google deal had fallen through and allowed Amazon to make the bid; Forbes reported that Google had backed out of the deal due to potential antitrust concerns surrounding it and its existing ownership of YouTube. The acquisition was closed on September 25, 2014.
Twitch is now operated as a wholly owned subsidiary of Amazon.com, with Emmett Shear remaining as CEO. Shear touted the Amazon Web Services platform as an "attractive" aspect of the deal, and that Amazon had "built relationships with the big players in media," which could be used to the service's advantage—particularly in the realm of content licensing. The purchase of Twitch marked the third recent video gaming–oriented acquisition by Amazon, which had previously acquired the developers Reflexive Entertainment and Double Helix Games.
On December 9, 2014, Twitch announced it had acquired GoodGame Agency, an organization that owns the eSports teams Evil Geniuses and Alliance. In March 2015, Twitch reset all user passwords and disabled all connections to external Twitter and YouTube accounts, after the service reported that someone had gained "unauthorized access" to the user information of some Twitch users.
In June 2016, Twitch added a new feature known as "Cheering", a special form of emoticon purchased as a microtransaction using an in-site currency known as "Bits". Bits are bought using Amazon Payments, and cheers act as donations to the channel. Users also earn badges within a channel based on how much they have cheered. 
On August 16, 2016, Twitch acquired Curse, Inc., an operator of online video gaming communities and gaming-oriented VoIP software.  In December 2016, GoodGame Agency was divested by Amazon to their respective members due to conflict of interest concerns.  On September 30, 2016, Twitch announced Twitch Prime, a service which provides premium features that are exclusive to users who have an active Amazon Prime subscription. This includes advertising-free streaming, and monthly offers of free add-on content ("Game Loot") and game discounts. 
In December 2016, Twitch announced a semi-automated chat moderation tool, which uses natural language processing and machine learning to set aside potentially unwanted content for human review.  In February 2017, Twitch announced that it would allow users to purchase games through the service, with major launch partners such as Paradox Interactive, Telltale Games, and Ubisoft. Links to purchase an eligible game will be displayed within Twitch's browsing interface, and partners can opt to display a purchase button on their stream when an eligible game is being played. If a game is bought via a stream's purchase link, the respective channel receives a 5% commission on the sale. Users also receive a "Twitch Crate" on every purchase, which includes Bits and a collection of random emoticons.   
Twitch and Blizzard Entertainment signed a two-year deal in June 2017 to make Twitch be the exclusive streaming broadcaster of select Blizzard eSports championship events, with viewers under Twitch Prime earning special rewards in various Blizzard games. 
In August 2017, Twitch announced it had acquired video indexing platform ClipMine. 
Content and audience
Twitch is designed to be a platform for hot content, including eSports shorts tournaments, personal streams of individual players, and gaming-related talk shows.  A number of channels do live speedrunning.  The Twitch homepage currently displays games based on viewership. The typical viewer is male and aged between 18 and 34 years of age, although the site has also made attempts at pursuing other demographics, including women.   As of December 2016 some of the most popular games streamed on Twitch are League of Legends, Hearthstone, and Dota 2 with a combined total of over 174 million hours watched. 
Twitch has also made expansions into non-gaming content; such as in July 2013, the site streamed a performance of 'Fester's Feast' from San Diego Comic-Con, and on July 30, 2014, electronic dance music act Steve Aoki broadcast a live performance from a nightclub in Ibiza.    In January 2015, Twitch introduced an official category for music streams, such as radio shows and music production activities, and in March 2015, announced that it would become the new official live streaming partner of the Ultra Music Festival, an electronic music festival in Miami. 
On October 28, 2015, Twitch launched a second non-gaming category, "Creative", which is intended for streams showcasing the creation of artistic and creative works. To promote the launch, the service also streamed an eight-day marathon of Bob Ross ' The Joy of Painting. In July 2016, Twitch launched "Social eating" as a beta; it was inspired by the Korean phenomenon of Muk-bang and Korean players having engaged in the practice as intermissions on their gaming streams. 
In March 2017, Twitch added an " IRL " channel that allows users to stream video doing just about anything.  The channel is normally in the top 10 most watched channels. Former Twitch IRL streamer Paul "Ice Poseidon" Denino was described by Will Partin of Rolling Stone as a "pioneer 'life streamer'" who "streams several hours of his conspicuously eventful life almost every single day." 
Broadcasters on Twitch often host streams promoting and raising money towards charity. By 2013, the website has hosted events which, in total, raised over US$8 million in donations for charitable causes, such as Extra Life 2013. As of 2017 the website has raised over US$75 million in donations for charitable causes.
In late 2013, particularly due to increasing viewership and using a legacy Adobe Flash plugin to present video to desktop users, Twitch had issues with lag, predominantly in Europe.  Twitch has subsequently added new servers in the region. Also in order to address these problems, Twitch implemented a new video system shown to be more efficient than the previous system. Initially, the new video system was criticized by users because it caused a significant stream delay, interfering with broadcaster-viewer interaction. Twitch staff said that the increased delay was likely temporary and at the time, was an acceptable tradeoff for the decrease in buffering.
The banning of Yandere Simulator was criticized by its anonymous developer, who believed that the game was being arbitrarily singled out with no explanation, as Twitch has not banned other games with similarly excessive sexual or violent content such as Mortal Kombat X, Grand Theft Auto, or The Witcher 3.  
Twitch features a large number of emoticons called emotes. There are emotes free for all users, emotes for Turbo users, emotes for Twitch Prime users, and emotes for users who are subscribed to Twitch partners.  Kappa is the most used emote on Twitch.  Twitch partnered broadcasters unlock more "emote slots" as they gain more subscribers up to a maximum of 50 emotes per channel. 
Partner and affiliate programs
Similar to the Partner Program of other video sites like YouTube, the Partner Program allows popular content producers to share in the advertisement revenue generated from their streams. Additionally, Twitch users can subscribe to partnered streamers' channels for US$4.99 a month, often granting the user access to unique emoticons, live chat privileges, and other various perks. Twitch retains US$2.50 of every US$4.99 channel subscription, with the remaining US$2.49 going directly to the partnered streamer.  Although exceptions can be made, Twitch requires that prospective partners have an "average concurrent viewership of 500+", as well as a consistent streaming schedule of at least three days a week.  Amazon Prime subscribers may freely subscribe to a user once every 30 days.  On April 19, 2017, Twitch announced that it would allow channels to offer higher-priced subscription tiers alongside the lowest US$4.99 tier. 
In April 2017, Twitch launched its Affiliate Program  that allows smaller channels to generate revenue as well. The participants of this program get some, but not all of the benefits of the Twitch Partners. As of April 26,  the streamers could make profit from cheering with Bits which are purchasable from Twitch directly. As of June 27, affiliates are now able to access the Twitch Subscriptions feature, with all the same functionality that Partners have access to, alongside one subscribe emote.  Affiliates are currently unable to receive revenue from ads, but Twitch has stated they plan to introduce this functionality in the future. The criteria to qualify to the affiliate program is currently as follows:
- Have at least 500 total minutes broadcast in the last 30 days.
- Have at least 7 unique broadcast days in the last 30 days.
- Have an average of 3 concurrent viewers or more over the last 30 days.
- Have at least 50 Followers.
Advertising on the site has been handled by a number of partners. In 2011, Twitch had an exclusive deal with Future US. On April 17, 2012, Twitch announced a deal to give CBS Interactive the rights to exclusively sell advertising, promotions and sponsorships for the community.   On June 5, 2013, Twitch announced the formation of the Twitch Media Group, a new in-house advertisement sales team which has taken over CBS Interactive's role of selling advertisements.
Twitch CEO Emmett Shear has stated a desire to support a wide variety of platforms, stating that they wanted to be on "every platform where people watch video".  Twitch streaming apps are available for mobile devices and video game consoles, including Android and iOS,  as well as PlayStation 4, PlayStation 3, Xbox One, and Xbox 360 video game consoles.  
PlayStation 4 and Xbox One video game consoles include built-in support for streaming to Twitch.   Twitch has been integrated into PC software, including video streaming to Twitch directly from EA's Origin software,  Ubisoft's Uplay,  games played on modern Nvidia video cards (via the driver's ShadowPlay feature),  and games such as Eve Online,  PlanetSide 2 and the Call of Duty franchise. :40 Players also have the ability to link their Twitch accounts with accounts on Valve's Steam.  In 2013, Twitch released a software development kit to allow any developer to integrate Twitch streaming into their software. 
In 2015, Twitch first held TwitchCon, a convention devoted to Twitch and the culture of video game streaming.  The inaugural TwitchCon was held at the Moscone Center in San Francisco from September 25–26, 2015. Since its inception TwitchCon has been an annual event. The second annual TwitchCon was held in San Diego at the San Diego Convention Center from September 30 - October 2, 2016.  The third annual TwitchCon was held in Long Beach, California at the Long Beach Convention and Entertainment Center from October 20-22, 2017. 
Twitch will be the subject of an upcoming Canadian documentary film titled "Stream On," featuring top streamers like Scarra, Pokimane, Lilypichu and Ellohime,  as well as one now in production by the National Film Board of Canada and Arte, which will incorporate footage from a Twitch channel called "Streamers Doc", hosting live panels about game streaming. 
As a teaching tool
A 2017 study examined and compared the teaching performance of novices and experts in video game instruction.  Over Twitch, novices can educate to similar levels to experts. People who score high on agreeableness or neuroticism (two of the Big Five personality traits) learn better from novice instructors than do those who score lower on either scale. The nature of Twitch also allows learners to interact with each other and the instructor. Extroverts benefit from this interaction while introverts do not.