ECO reference

ECO codes, explained.

The Encyclopaedia of Chess Openings sorts every opening into five volumes, A through E. The letter tells you the family at a glance — a code beginning with B is a semi-open game, one beginning with E is an Indian defence. Browse a volume to see its main lines and the ideas behind them.

Flank & English openings

31 openings

Flank openings and the English — controlling the centre from the wings, and everything that isn't 1.e4 or 1.d4.

Browse volume A

Semi-open games (Sicilian, Caro-Kann, Pirc)

35 openings

The semi-open games — Black answers 1.e4 with something other than 1…e5: the Sicilian, Caro-Kann, Pirc and Alekhine.

Browse volume B

Open games & the French

42 openings

The open games and the French — 1.e4 e5 (Ruy López, Italian, gambits) together with 1.e4 e6.

Browse volume C

Closed games & the Queen's Gambit

28 openings

The closed games and the Queen's Gambit — 1.d4 d5 and the symmetrical Queen's-pawn structures.

Browse volume D

Indian defences

14 openings

The Indian defences — 1.d4 Nf6 systems: Nimzo-, Queen's and King's Indian and their cousins.

Browse volume E

Looking for a specific line? Browse all openings by name.