The Universal Chess Interface (UCI) is a open free, Chess communication protocol used to enable the engine portion of a chess program to communicate with a graphical user interface.
It was designed and released by Rudolf Huber and Stefan Meyer-Kahlen in Nov 2000 , and can be seen as a rival to the older and more established Xboard/Winboard Communication protocol. Like the later, it is free to use without license fees.
Only a few interfaces and engines supported this protocol, until Chessbase - the powerhouse chess software company which markets Fritz, began to support UCI in 2002. As of 2003, there are about 50 engines which support UCI and interfaces like Fritz, Chess Assistant, Chess Partner, Knights and Arena.