Online chess is chess that is played over the internet, allowing players to play against each other in real time. This is done through the use of Internet chess servers, which pair up individual players based on their rating using an Elo or similar rating system.
Online chess has existed in various forms including PLATO and play-by-email since the dawn of the Internet in the 1970s. The first website designed for online chess was the Internet Chess Club, which started operation in 1992. Since then, a number of chess websites have been developed. These include Chess.com, Lichess, and chess24, which are the largest chess websites as of 2021.
Online chess saw a spike in growth during the quarantines of the COVID-19 pandemic. This was due to both isolation and the popularity of Netflix miniseries The Queen's Gambit, which was released in October 2020. Chess app downloads on the App Store and Google Play Store rose by 63% after the show debuted. Chess.com saw more than twice as many account registrations in November as it had in previous months, and the number of games played monthly on Lichess doubled as well. There was also a demographic shift in players, with female registration on Chess.com shifting from 22% of new players to 27% of new players. Grandmaster Maurice Ashley said "A boom is taking place in chess like we have never seen maybe since the Bobby Fischer days," attributing the growth to an increased desire to do something constructive during the pandemic. USCF Women's Program Director Jennifer Shahade stated that chess works well on the internet, since pieces do not need to be reset and matchmaking is virtually instant.
Online chess livestreaming also saw a surge amidst the pandemic. Players like Grandmaster Hikaru Nakamura streamed chess via Twitch, with more than 41 million hours of chess being watched total on the platform from March to August 2020. Nakamura and other high-level chess streamers created PogChamps during the pandemic, an amateur tournament streamed on Twitch that was at one point the top-viewed stream on the platform.
Chess websites pair players based on their rating, which is usually based on the Elo or Glicko/Glicko-2 rating system. After a game ends, scores are updated immediately and players may search for a new game using their updated ratings.
Over-the-board (OTB) chess is traditionally played with a slow time control, meaning players are allowed more time to consider moves. Online chess is often played faster, with 93.8% of live chess games on Chess.com being played with a time control of 10 minutes per side or faster. International Master Anna Rudolf said that "online chess' shift to speed chess has brought excitement to the game."
Online cheating is an issue that has had a large effect on all levels of play. This is usually achieved by using a chess engine to get the best moves in a given position, though it can take other forms including sandbagging and rating manipulation. Chess.com stated in August 2020 that they were closing roughly 500 accounts each day due to cheating, some of whom were Grandmasters.
High-level chess tournaments were largely forced online during the COVID-19 pandemic, including the FIDE Online Nations Cup and the Magnus Carlsen Chess Tour. These were played on websites like Chess.com and chess24, but enforced additional rules on webcam usage in order to prevent cheating. Some tournaments also disallowed leaving the computer for breaks or to walk around, which would usually be allowed in an in-person tournament.
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