Place a number from 1 to X (integers only) into each cell so that each number appears exactly once in each row and column. (X is the number of cells in each row.) Some inequality relations are given between adjacent cells; they must apply to the numbers in those cells.
(Rules and example from PGP IB)
History of the puzzleEdit
First appeared on Nikoli vol. 92 (2000) under the name Dainarizumu (ダイナリズム < Dainari (greater than) + izumu (-ism)). Rules were suggested by Asaokitan (あさおきたん). It later evolved into Mainarizumu, present on pzv.jp and puzz.link. 
The name Futoshiki means "inequality" in Japanese and probably was given when it was published by The Guardian in 2006.
A similar puzzle (without Latin square constraint) called "Relationen" (Relations) has appeared in German Nationals 1995.