Chess terms explained

Chess has a vocabulary, and commentators use it as if everyone was born knowing it. Gambit, tempo, fianchetto, luft, en prise, the exchange, a passed pawn, a bad bishop, a fortress. Each page here takes one term, defines it in a sentence, and then shows it on a board, because 'an outpost is a square a pawn cannot attack' means nothing until you see the knight on d5 that Black can never remove. The tactical words (fork, pin, skewer, discovered attack, zugzwang and the named mates) each have a full page in the patterns section, linked at the bottom.

1. What is a gambit in chess?

   A gambit is material offered on purpose in the opening, almost always a pawn, in exchange for something a pawn cannot buy: a lead in development, a share of the centre, or open lines for your pieces.

2. What is tempo in chess?

   A tempo is a single move counted as time.

3. What is a fianchetto in chess?

   A fianchetto is putting a bishop on b2, g2, b7 or g7, behind a knight pawn that has moved one square.

4. Blunder, mistake, inaccuracy: what the symbols mean

   A blunder (?

5. What is an open file (and a half-open file)?

   An open file is a file with no pawns of either colour on it, so a rook or queen sees from one end of the board to the other.

6. What is an outpost in chess?

   An outpost is a square in or near your opponent's half of the board that you can defend with a pawn, and that no enemy pawn will ever be able to attack.

7. What is a passed pawn in chess?

   A passed pawn is one with no enemy pawn ahead of it on its own file or on either file next door, so nothing but a piece can stop it reaching the eighth rank.

8. What is an isolated pawn in chess?

   An isolated pawn has no pawn of its own colour on either file next to it, which means no pawn will ever be able to defend it: only pieces can.

9. What are doubled pawns in chess?

   Doubled pawns are two of your own pawns on the same file, which can only happen after a capture.

10. What is a backward pawn in chess?

    A backward pawn is one that has fallen behind the pawns on the files either side of it, so no pawn can defend it, and cannot advance because the square in front is covered by the enemy.

11. What is pawn structure in chess?

    Pawn structure is the pattern the pawns make on the board, ignoring the pieces.

12. What is a pawn chain in chess?

    A pawn chain is a diagonal row of pawns of the same colour, each one defending the pawn in front of it.

13. What does material mean in chess?

    Material is the pieces and pawns you have on the board, counted in points: pawn 1, knight 3, bishop 3, rook 5, queen 9.

14. What is 'the exchange' in chess?

    The exchange is a rook traded for a bishop or a knight, five points against three.

15. Minor pieces and major pieces explained

    Bishops and knights are minor pieces, three points each.

16. What is development in chess?

    Developing a piece means moving a knight or a bishop off its starting square to somewhere it does real work, and tucking the king away by castling.

17. What is initiative in chess?

    You have the initiative when your opponent is answering your moves instead of making his own.

18. What is luft in chess?

    Luft is German for air: the square you make for your castled king by pushing the h-pawn (sometimes the g-pawn) one square, so that a check along the back rank is not mate.

19. What does en prise mean?

    A piece is en prise (French, roughly 'in take') when it stands on a square where the opponent can capture it and give nothing back.

20. What does it mean to trade pieces?

    A trade is a capture that gets captured back, so both sides lose roughly the same material: knight for knight, rook for rook.

21. What is simplification in chess?

    Simplifying means trading pieces off until the position is easy to play, normally an endgame.

22. What are 'theory' and 'book moves'?

    Theory is the body of known moves, mostly openings, worked out over a century of games and stored in books and databases.

23. What is a novelty in chess?

    A novelty is a move played for the first time in a known position: the point where a game leaves the database.

24. What is prophylaxis in chess?

    A prophylactic move does nothing for your own plan and everything against his: h3 to keep a bishop out of g4, a3 to keep a knight out of b4, Kh1 to step off a dangerous diagonal.

25. What is a desperado in chess?

    A desperado is a piece that cannot be saved, so instead of trying to rescue it you use it: it captures the most valuable thing it can reach, or throws itself at the enemy king to force a draw.

26. What is a windmill in chess?

    A windmill is a repeating discovered check.

27. What is the Greek gift sacrifice?

    The Greek gift is the bishop sacrifice Bxh7+ against a castled king.

28. What is overloading in chess?

    An overloaded piece is a defender with two jobs it cannot do at the same time: guarding a piece and guarding a mating square, say.

29. What is a weak square (a hole)?

    A weak square, usually called a hole, is a square in your own half that none of your pawns can ever attack again, because the pawns that used to cover it are gone or have marched past.

30. What is space in chess?

    Space means the squares your pawns control in front of them, and therefore the room your pieces have to move.

31. What is counterplay in chess?

    Counterplay means creating your own threats instead of only answering your opponent's.

32. What is a mating net in chess?

    A mating net is a set of pieces arranged so that mate cannot be stopped, even though nothing is in check yet.

33. What do +1.0 and centipawns mean?

    An engine scores a position in pawns, always from White's point of view.