Editing Computer chess (section)

=== Graphical user interface ===
Computer chess programs usually support a number of common ''de facto'' standards. Nearly all of today's programs can read and write game moves as [[Portable Game Notation]] (PGN), and can read and write individual positions as [[Forsyth–Edwards Notation]] (FEN). Older chess programs often only understood [[algebraic chess notation|long algebraic notation]], but today users expect chess programs to understand standard [[algebraic chess notation]].

Starting in the late 1990s, programmers began to develop separately ''engines'' (with a [[command-line interface]] which calculates which moves are strongest in a position) or a ''[[graphical user interface]]'' (GUI) which provides the player with a chessboard they can see, and pieces that can be moved.  Engines communicate their moves to the GUI using a protocol such as the Chess Engine Communication Protocol (CECP) or [[Universal Chess Interface]] (UCI). By dividing chess programs into these two pieces, developers can write only the user interface, or only the engine, without needing to write both parts of the program. (See also [[chess engine]].)

Developers have to decide whether to connect the engine to an opening book and/or endgame [[tablebase]]s or leave this to the GUI.