The ELO system for rating chessplayers was named after its originator, Arpad Elo. Born in 1903, Elo emigrated to the USA when he was 10. Educated at Chicago University, he later became professor of physics at Marquette University, Milwaukee. He learned to play chess in his teens and played in a number of tournaments. He was champion or co-champion of Wisconsin 9 times between 1935 and 1961. He was active in the USCF (United States Chess Federation) from its founding in 1939. He spent 20 years developing and validating his chess rating system, which was adopted by FIDE in 1970 for international use.His book 'The Rating of Chessplayers, Past and Present' was published in 1978 and is the definitive reference on the ELO rating system. Most chess organisations that perform ratings for players use the ELO system, or a variation of it.