Tetris is a video puzzle game originally designed and programmed by Alexey Pajitnov in June 1985, while working for the Dorodnicyn Computing Centre of the Academy of Science of the USSR in Moscow. He derived its name from the Greek numerical prefix "tetra-", as all of the pieces contain four segments, and tennis, Pajitnov's favorite sport.

The game (or one of its many 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 and even as an Easter egg on non-media products like oscilloscopes.

It has even been played on the sides of various buildings, with the record holder for the world's 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.