Chess notation is the term for systems that record the moves made during a game of chess. Several different notational systems are in use. Each system describes the piece involved in a move, its ending location (and sometimes its starting location), and any resulting effect (capture, promotion, check, checkmate, etc.). There are two main types of chess notation: descriptive and algebraic.
'Chess notation' can also refer to systems that record the position of all the pieces on a chess board at one specific point in the game. This is useful for adjourning a game to resume later or for conveying chess problem positions without a diagram. The Forsyth-Edwards Notation (FEN) is the main system for this.
Descriptive notation is also sometimes called English notation. Until the late 1970s, at least in English-speaking countries, chess games were recorded and published using this notation. It is used nowadays by a dwindling minority of players. However, studying older chess books still requires an understanding of descriptive notation. Descriptive notation has several advantages, the most notable being that the symmetrical nature of chess strategy is clearer to see in descriptive notation.
Algebraic chess notation is more compact than descriptive chess notation. Originally developed because computer programs required algebraic input, algebraic notation is now the most widely used method for recording the moves of a game of chess. An individual accustomed to just one system will naturally find that system to be more mistake-proof and readable; and most younger players are now more comfortable thinking in algebraic notation.
Both systems are explained in detail here at ChessNotation.com. However, we begin with the features they have in common:
When annotating chess games using either system, a question mark appended to a move labels the move as bad, and an exclamation point labels the move as especially good.
Castling is indicated by the special notation O-O for king-side castling and O-O-O for queen-side castling.
Both systems can cause confusion in international correspondence chess, because different languages have different names for the pieces. So a third standard, actually a variation on algebraic notation, has been developed, called ICFF Numeric Notation.
Another variation on algebraic notation, called Portable Game Notation (PGN) has emerged as a format more suitable for computer processing but still readable by humans. Finally, for situations where only computers are involved, there a notation system called StenoChess, which records games using the smallest data structures, but it is practically unreadable by humans.