PGN: Portable Game Notation
PGN
Definition
PGN stands for Portable Game Notation. It is a plain-text, human-readable standard for recording chess games move by move, together with supplemental information such as the players’ names, the event, date, result, opening, and even commentary. Created by American programmer Stephen J. Edwards in 1993, PGN quickly became the lingua franca of digital chess because it combines simplicity (a normal text file) with enough structure that computers can parse it reliably.
How PGN Is Used in Chess
- Game Archiving: Tournament directors and websites publish thousands of games in PGN so they can be downloaded, searched or fed into engines and databases.
- Training: Players build personal opening books or “game collections” by importing PGN files into software such as ChessBase, SCID, lichess studies, or mobile apps.
- Broadcast & Live Transmission: DGT electronic boards transmit moves in real time as PGN strings that flow straight to online viewers.
- Publishing: Authors embed PGNs in articles or books to let readers replay the moves on interactive boards.
File and Tag Structure
A complete PGN file is divided into metadata “tag pairs” and the movetext section.
- Tag Pairs: One line per tag, enclosed in brackets.
The original specification defines seven “STR
tags”, but authors can add any custom tag (e.g.,
[Opening "Najdorf Sicilian"],[ECO "B90"]). - Movetext: The actual moves written in algebraic
notation. Commentary may be inserted using
{curly braces}for prose or(parentheses)for variations. A terminal result code (1-0,0-1,½-½, or*) ends the movetext.
[Event "FIDE Candidates"] [Site "Berlin GER"] [Date "2018.03.10"] [Round "1"] [White "Kramnik, Vladimir"] [Black "Aronian, Levon"] [Result "1-0"] [ECO "C65"] [Opening "Berlin Defence"] 1. e4 e5 2. Nf3 Nc6 3. Bb5 Nf6 4. d3 Bc5 5. c3 O-O 6. O-O Re8 7. Re1 a6 8. Ba4 b5 9. Bc2 d6 10. h3 h6 11. Nbd2 Bb6 12. Nf1 ... 32. Rg8# 1-0
Strategic & Historical Significance
Although PGN does not influence over-the-board strategy, its role in the information age has strategic consequences:
- Opening Preparation: Because virtually every top-level game is published in PGN within hours, grandmasters and engines can prepare deeply against future opponents.
- Democratization of Knowledge: Prior to PGN, access to large game collections required expensive printed volumes. Free PGN databases (e.g., “The Week in Chess”) have flattened that hierarchy.
- Data-Driven Insights: Statisticians sift millions of PGNs to study drawing tendencies, the rise of 1. d4, or the declining popularity of the King’s Gambit.
Examples
Below is a miniature PGN fragment of the famous “Opera Game” (Morphy vs. Duke & Count, Paris 1858) that you can replay:
The PGN stores the entire tactical sequence that culminates in 25. Rd8#, immortalizing Morphy’s combination for posterity.
Interesting Facts & Anecdotes
- First Public Database: The inaugural PGN collection contained 2,000 master games and fit on a single 3.5-inch floppy disk.
- Kasparov’s Surprise: During the 1997 match Kasparov vs. Deep Blue, IBM programmers produced fresh PGNs of the engine’s practice games. Kasparov’s team tried to glean opening clues—only to be swamped by thousands of lines!
- Emoji in PGN: The standard technically allows any printable ASCII, so creative online users have sneaked in emoji ⏳ or hashtags in comments, though most engines ignore them.
- World Record File: As of 2024, the “KingBase” project offers 4 million+ games in a single PGN that surpasses 6 gigabytes uncompressed.
Quick Reference
- File extension:
.pgn - Encoding: Usually UTF-8 today, though ASCII remains compatible.
- Sibling format: FEN records a single board state; PGN records an entire game.