Tetris (Lang-ru???????) is a puzzle video game originally designed and programmed by Alexey Pazhitnov in the Soviet Union. It was created on June 6, 1984, while he was working for the Dorodnicyn Computing Centre of the Academy of Science of the USSR (Russian Academy of Sciences) in Moscow. He derived its name from the Greek (Ancient Greek) numerical prefix tetra- (all of the games pieces, known as Tetrominoes, contain four segments) and tennis, Pazhitnovs favorite sport.Pajitnov interview, G4 (G4 (TV channel)) "Icons (Icons (TV series))", ep. 305, originally aired on April 22, 2004.

The Tetris game is a popular use of tetrominoes, the four element special case of polyominoes. Polyominoes have been used in popular puzzles since at least 1907, and the name is given by the mathematician Solomon W. Golomb in 1953. However, even the enumeration of pentominoes is dated to antiquity.

The game (or one of its many variants (List of Tetris variants)) is available for nearly every video game console and computer operating system, as well as on devices such as graphing calculators, mobile phones, portable media players, PDAs (Personal digital assistant), Network music players (Internet radio device) and even as an Easter egg (Easter egg (media)) on non-media products like oscilloscopes. It has even inspired Tetris serving dishes and been played on the sides of various buildings, with the record holder for the worlds largest fully functional game of Tetris being an effort by Dutch students in 1995 that lit up all 15 floors of the Electrical Engineering department at Delft University of Technology.

While versions of Tetris were sold for a range of 1980s home computer platforms, it was the hugely successful handheld version (Tetris (Game Boy)) for the Game Boy launched in 1989 that established the reputation of the game as one of the most popular ever. Electronic Gaming Monthlys 100th issue had Tetris in first place as "Greatest Game of All Time". In 2007, Tetris came in second place in IGNs "100 Greatest Video Games of All Time". It has sold more than 70 million copies. In January 2010, it was announced that Tetris has sold more than 100 million copies for cell phones alone since 2005.