What is NCO?

NCO stands for Nunn's Chess Openings. It is a reference book on chess openings authored by John Nunn, Graham Burgess, John Emms, and Joe Gallagher. The book provides comprehensive coverage of all chess openings, making it an invaluable resource for chess players of all levels. It offers both detailed explanations and clear illustrations, providing strategic analysis and tactical insight into a wide range of chess opening variations.