Short answers, pulled from the story.
Chess originated in 7th-century India as chaturanga, a game modeled on the four divisions of an ancient army. It spread to Persia around 600 A.D., then to the Arab world after the Islamic conquest of Persia between 633 and 651, and reached Western Europe by the 9th century, with modern rules crystallizing in Valencia, Spain around 1475.
Wilhelm Steinitz of Prague is recognized as the first official World Chess Champion, claiming the title in 1886 after defeating the leading German master Johannes Zukertort. Steinitz also pioneered a scientific, positional approach to chess that influenced all subsequent play.
In 1997, Deep Blue became the first computer to defeat a reigning World Chess Champion, beating Garry Kasparov in a six-game match. Chess engines have been stronger than the best human players since the early 2010s, and the game as a whole remains unsolved.
The Elo rating system, developed by Arpad Elo and used by FIDE, assigns numerical ratings to players; an average club player rates about 1500. The Grandmaster title requires a rating of at least 2500 and three qualifying norms, while International Master requires 2400, FIDE Master 2300, and Candidate Master 2200. Magnus Carlsen holds the all-time rating record of 2882.
The 2020 online chess boom was driven by a combination of COVID-19 pandemic isolation, the success of the Netflix series The Queen's Gambit, the popularity of online tournaments such as PogChamps, and the growth of chess streaming on platforms like Twitch. The first major internet chess server was launched by the University of Utah in 1992, and the commercial Internet Chess Club followed in 1995.
Emanuel Lasker, a German mathematician, held the World Chess Championship for 27 years, the longest tenure of any world champion in history. He won the title from Wilhelm Steinitz in 1894 and lost it to José Raúl Capablanca in 1921.