ChessWorld.net, founded in 2000, is an online chess site. Play relaxed, friendly correspondence-style chess — with online daily, turn-based games — at your own pace.

📚 Chess Courses – Openings, Tactics, Middlegame, Endgames

The ECO Code Index: A Guide to Opening Classifications (A00-E99)

If you look at a chess database, you will see cryptic codes like B90 or E15 next to the opening name. These come from the Encyclopedia of Chess Openings (ECO), the standard system for classifying every possible chess opening into five volumes (A through E).

🔥 Opening insight: Memorizing ECO codes is not the same as knowing the opening. You will get crushed if you don't understand the principles behind the moves. Master the ideas, not just the labels.

📘 Master Opening Principles

🔥 Get Chess Course Discounts

Volume A Flank Openings & Irregular Lines

A00 Irregular Openings (Grob, Polish)

A02-A03 Bird's Opening (1. f4)

A04-A09 Réti Opening

A10-A39 English Opening (1. c4)

A40-A44 Queen's Pawn (1. d4 without 1...d5)

A50-A79 Benoni & Benko Gambit

A80-A99 Dutch Defense

Volume B Semi-Open Games (Sicilian, Caro-Kann)

B00-B05 Alekhine's Defense