List of chess openings

This is a list of chess openings, organized by the "Encyclopaedia of Chess Openings" () code. In 1966, Chess Informant categorized the chess openings into five broad areas ("A" through "E"), with each of those broken down into one hundred subcategories ("00" through "99"). The openings were published in five volumes of "ECO", with volumes labeled "A" through "E". This is a list of chess openings by the "ECO" classification.
A – Flank openings.
A00–A39.
White first moves other than 1.e4, 1.d4: 
A40–A44.
1.d4 without 1...d5, 1...Nf6 or 1...f5: Atypical replies to 1.d4 
A45–A49.
1.d4 Nf6 without 2.c4: Atypical replies to 1...Nf6 
A50–A79.
1.d4 Nf6 2.c4 without 2...e6 or 2...g6: Atypical Indian systems 
A80–A99.
1.d4 f5: Dutch Defence 
B – Semi-Open Games other than the French Defense.
B00–B19.
1.e4 without 1...c5, 1...e6 or 1...e5 
B20–B99.
1.e4 c5: Sicilian Defence 
C – Open Games and the French Defense.
C00–C19.
1.e4 e6: French Defence 
C20–C99.
1.e4 e5: Open Game 
D – Closed Games and Semi-Closed Games.
D00–D69.
1.d4 d5: Closed Game 
D70–D99.
1.d4 Nf6 2.c4 g6 with 3...d5: Grünfeld Defence 
E – Indian Defenses.
E00–E59.
1.d4 Nf6 2.c4 e6: Indian systems with ...e6 
E60–E99.
1.d4 Nf6 2.c4 g6 without 3...d5: Indian systems with ...g6 (except Grünfeld) 
Statistics.
These statistics show a movement away from symmetrical defences to asymmetrical defences. In particular, in reply to 1.e4, the Sicilian and French defences, and to 1.d4 the Indian defences. Also, particularly amongst strong players, an increased use of the English Opening for White.