A small word.
A better game.

A pin against the king. The pinned piece cannot legally move off the line, because that would expose its own king to check.

A king participating in the fight, supporting pawns or attacking targets once mating danger has diminished.

How effectively a piece influences the position. Useful squares and threats matter more than the number of legal moves alone.

A historical practice of pausing a long game overnight and resuming it later. The sealed move was written down and kept by the arbiter. Engines made adjournments obsolete, and they disappeared in the 1990s.

A favourable imbalance in material, activity, space, king safety or pawn structure.

The standard way to record moves. Files are a to h, ranks 1 to 8, pieces are K, Q, R, B and N, and pawns have no letter. For example, Nf3 means a knight moves to f3, and exd5 means the e-pawn captures on d5.

Studying a position and its possible continuations to understand the best plans and moves.

A comment, symbol or variation added to a game score to explain the play.

The official who supervises a chess competition and applies its rules.

A deciding game in which a draw counts as success for one side, usually Black, with unequal clock times determined by the event.

A threat against a piece or square. An attacked piece is not necessarily lost if it is adequately defended.

Luring a defending piece onto a square where it becomes vulnerable. Often used as another name for decoy.

Checkmate by a rook or queen on the first or last rank, against a king trapped behind its own pawns.

A pawn that cannot safely advance and has fallen behind neighbouring pawns that cannot defend it.

A bishop restricted by its own pawns on the same colour squares. It can still be useful defensively.

Two pieces lined up on the same rank, file or diagonal, such as two rooks on an open file or a queen behind a bishop.

An optional feature in some online arenas that trades part of a player's clock time for a possible scoring bonus.

A move judged strongest in a position under a particular analysis or objective.

A piece that moves diagonally and stays on one colour of square throughout the game.

Having both bishops while the opponent does not. In open positions the two bishops together are usually worth a little more than bishop and knight.

Playing without seeing the board, relying on a mental picture and communicated moves.

Fast chess. Under the FIDE Laws, the initial time plus 60 increments is 10 minutes or less per player. Common online formats include 3+0 and 5+0.

Stopping a pawn's advance by placing a piece directly in front of it. Knights often make effective blockaders.

A very bad move that loses material or the game. Engines label a move a blunder when it drops the mover's winning chances sharply.

A move found in established opening theory.

A pawn sequence, sometimes sacrificing several pawns, that creates an unstoppable passer or entry route.

An informal praise label for an unusually strong or surprising move. Platform-specific labels use different criteria.

Using a rook to shield its king from checks so a pawn can promote, as in the Lucena technique.

A very fast time control, usually one or two minutes per player for the whole game.

A round in which a player does not play a game. Points awarded depend on the event and the type of bye.

Examining possible move sequences and their resulting positions before choosing a move.

The short list of moves worth calculating in a position. Choosing good candidates is the first step of calculation.

A move that removes an opposing piece from the board and places the capturing piece on its square, except in en passant.

A special move of king and rook together, tucking the king to safety and connecting the rooks.

O-O records kingside castling; O-O-O records queenside castling in standard algebraic notation.

One hundredth of a pawn. Engines report evaluations in centipawns, so +150 means White is better by about a pawn and a half.

Bringing pieces toward central squares where they can influence more of the board.

Also known as Centralization

The four squares d4, e4, d5 and e5. Control of these squares gives pieces access to both wings.

Also known as Center

An attack on the king. The player in check must escape it immediately.

The plus sign (+) after a move in common algebraic notation, indicating check.

Check with no legal way out. It ends the game.

A variant, also called Fischer Random, where the back-rank pieces are shuffled into one of 960 starting positions so that opening preparation matters less.

A slow time control, typically 90 minutes or more per player. Most world championship games are classical.

A central pawn presence, especially pawns on d4 and e4 for White or d5 and e5 for Black.

Moving or sacrificing a piece to free a square or line for another piece.

An opening beginning 1.d4 d5. Individual variations can still lead to open positions.

A position with blocked pawn chains that restrict long-range pieces and reward manoeuvring or pawn breaks.

A group of squares of one colour. Weaknesses on that colour can become important after its bishop is exchanged.

A calculated sequence of moves, often involving a sacrifice, that achieves a concrete goal.

Advantages that offset a disadvantage, such as an attack in return for sacrificed material.

Passed pawns on neighbouring files. They can support one another as they advance, especially when one is a rank ahead.

Turning an existing advantage into a win through accurate play.

Pieces working together toward a common purpose, supporting one another's threats and defences.

Chess played by exchanging moves remotely over extended time periods. Assistance rules depend on the organiser.

Pairs of squares linked by a defensive requirement: when one king occupies one square, the other must often occupy its partner.

An opening in which a player responds to an opponent's play with a material offer of their own.

Active chances for the defending side, used to distract the opponent from their own plan.

Answering a check by blocking its line with a move that also checks the opposing king.

A king kept away from important squares by an enemy rook or queen along a rank or file.

One of the board's darker-coloured squares. A dark-squared bishop stays on these squares.

A position in which neither player can checkmate by any legal sequence; the game is drawn immediately.

A sacrifice that lures an enemy piece onto a particular square where it can be attacked or exploited.

Protecting a piece, square or position against a threat. Active defence often creates threats of its own.

Also known as Defense

Giving up material to stop an attack, reach a drawable ending or obtain counterplay.

A tactic that forces a defending piece away from the square or piece it protects.

A clock setting that waits a fixed time at the start of each turn before subtracting main time; unlike increment, unused simple delay does not accumulate.

A measure of how far an engine has searched, usually reported in plies. Selective search means not every line is explored equally far.

A piece that is lost anyway and is used to capture as much material as possible before it goes.

Moving pieces off their starting squares toward useful posts in the opening.

Having more pieces usefully mobilised than the opponent, which can justify opening the position quickly.

A slanting line of squares of the same colour. Bishops move along diagonals.

Kings facing one another on a diagonal, used to control access to important squares.

Moving one piece to uncover an attack by another piece standing behind it. If the uncovered attack is on the king, it is a discovered check.

A check revealed when one piece moves out of the line of another piece.

Kings facing one another with an odd number of squares between them, extending the idea of direct opposition.

Restricting an enemy piece so severely that it has no useful or safe moves.

A move that creates two threats at once. A fork is a common form of double attack.

Check from two pieces at once, usually created by a discovered check. Only a king move can answer it.

Two threats created by the same move, which may involve different pieces or targets.

Two pawns of the same colour on the same file, usually after a capture. They are often weak because they cannot protect each other.

A game with no winner. It can come from agreement, stalemate, repetition, the fifty-move rule or insufficient material.

A request for a draw based on a qualifying rule, such as threefold repetition or the fifty-move rule.

A proposal to end the game as a draw, which the opponent may accept or decline subject to event rules.

An advantage based on temporary activity, threats or initiative that may disappear if not used.

A code from A00 to E99 in the Encyclopaedia of Chess Openings classification system.

A rating system invented by Arpad Elo. The difference between two ratings predicts the expected score: a player rated 200 points higher is expected to score about 76 percent.

A pawn capture of an enemy pawn that has just made a two-square move past it.

A piece exposed to capture. Whether taking it is good depends on defenders, tactics and compensation.

Also known as In take

The final phase of the game, when few pieces remain and the kings become active fighting pieces.

Software that searches chess positions and evaluates candidate moves.

A judgement of which side stands better and why. Numerical engine evaluations depend on the engine and settings.

A trade of pieces. "Winning the exchange" means winning a rook for a bishop or knight.

Giving up a rook for a bishop or knight in return for positional or tactical compensation.

An informal name for a fork that attacks a king, queen and rook at once.

Forsyth-Edwards Notation, a single line of text that describes a position: piece placement, side to move, castling rights, en passant square and move counters.

Developing a bishop to b2, g2, b7 or g7 after moving the knight's pawn one square, so the bishop controls the long diagonal.

The International Chess Federation, responsible for international chess governance, ratings and titles.

A draw rule: fifty moves by each side without a capture or pawn move allows a draw claim.

A vertical column of the board, labelled a to h.

The game is automatically drawn when the same position, with the same legal possibilities and side to move, occurs five times.

The indication that a player's allotted time has expired.

An opening begun with a move away from the central d- and e-pawns, such as 1.c4 or 1.Nf3.

A sequence in which one side can guarantee checkmate against every defence.

A move that sharply limits useful replies. Checks, captures and direct threats are common candidates.

A single piece attacking two or more enemy pieces at once. Knight forks are the most common.

A defensive arrangement that the stronger side cannot penetrate despite a material advantage.

An opening in which a player offers material, usually a pawn, for faster development or attacking chances.

An opening continuation in which the opponent takes the offered material.

An opening continuation in which the opponent chooses not to take the offered material.

The recorded sequence of moves in a game, often with player and event details.

A bishop with useful open diagonals, often operating on the opposite colour from its own central pawns.

The highest standard over-the-board FIDE playing title, commonly earned through qualifying norms and reaching a 2500 rating. Specific direct-title routes also exist.

A bishop sacrifice on h7 or h2 against a castled king, often followed by knight and queen checks. It works only when the follow-up is sufficient.

Describes a piece exposed to capture without sufficient compensation. It may be undefended or inadequately defended.

Two friendly pawns on adjacent files with no friendly pawns on neighbouring outer files, usually abreast in the centre.

An undefended piece that is attacked, or that can be attacked for free.

A weak square in or near a pawn formation that cannot be controlled by the side's pawns.

A player's starting rank for the pieces: rank 1 for White and rank 8 for Black.

An enemy pawn that can be attacked by a pawn advance to open lines, especially near the king.

An engine or player's failure to see a consequence just beyond the depth of the calculation.

An opening approach that allows an opponent to occupy the centre and then attacks it with pieces and pawn breaks.

A move that violates the rules, such as moving a rook diagonally or leaving your king in check.

A move that makes a piece or the overall position more effective without necessarily creating an immediate threat.

An unexpected move inserted before an anticipated reply, often a forcing check. Also called zwischenzug.

A move that worsens a position modestly compared with stronger alternatives; classification depends on the analysis method.

Time added to a player's clock after each move, for example the 2 in 3+2.

The ability to make threats that force the opponent to react, so that you keep choosing the course of the game.

A position where neither side can checkmate by any series of legal moves, such as king against king. The game is drawn.

A tactic that places a piece on a line between an enemy piece and the square it defends.

A check played before the expected move, often before a recapture.

A FIDE title below grandmaster, usually earned through qualifying norms and a rating requirement.

A pawn with no friendly pawns on the neighbouring files. It cannot be defended by pawns, but it often gives its owner active piece play.

French for "I adjust". Said before touching a piece only to straighten it on its square, so the touch-move rule does not apply.

A square whose occupation by the king guarantees a particular objective, often promoting a pawn under specified conditions.

The piece whose safety decides the game. It moves one square in any direction, but may never move into check.

How well the king is protected from threats, considering shelter, open lines and attacking pieces.

The half of the board consisting of the e-, f-, g- and h-files.

A piece that moves two squares along one axis and one along the other. It can jump over intervening pieces.

A format in which losing a match eliminates a player from the main competition.

A move permitted by the rules, including the requirement that your own king is not left in check.

One of the board's lighter-coloured squares. A light-squared bishop stays on these squares.

A basic winning rook ending with an advanced pawn and king near promotion, often won by building a rook bridge against checks.

German for "air". A pawn move in front of the castled king that gives it an escape square and prevents a back-rank mate.

A principal, well-studied continuation in an opening or analysis.

A rook or a queen. Also called a heavy piece.

A planned sequence that transfers pieces to better squares.

Also known as Maneuver

A position where the attacking side can force mate by its second move against all legal replies.

The hash sign (#) after a move in common algebraic notation, indicating checkmate.

The pieces and pawns each side has. Material balance is one factor in evaluating a position.

An arrangement of pieces that restricts the enemy king and creates mating threats.

A recurring arrangement of pieces that delivers checkmate.

The phase after the opening, when most pieces are still on the board and plans and tactics dominate.

A bishop or a knight.

Advancing a smaller pawn group against a larger group to create weaknesses, often on the queenside.

A significant error, generally less severe than a blunder. There is no universal numerical threshold.

The sequence in which moves are played. Small changes can allow or avoid important variations.

An engine setting that analyses multiple candidate lines rather than reporting only one principal variation.

A position in which either side would obtain a worse result if it were their turn to move.

A qualifying tournament performance toward certain titles, subject to detailed rating and event requirements.

A move new to established practice in a particular opening position, as far as the relevant records show.

A file with no pawns on it. Rooks are strongest on open files.

An opening beginning 1.e4 e5. The name describes the opening family, not necessarily the eventual pawn structure.

A position with few central pawn obstructions, giving long-range pieces room to operate.

The first phase of a game, when players develop pieces, contest the centre and arrange king safety.

Analysed opening moves and plans collected from games and study.

A tempting sequence containing a tactical pitfall that punishes a particular response.

Bishops on different square colours. They can favour the attacker with major pieces present, but often favour the defender in bishop endings.

Kings on the same line with one square between them. The side not to move has the opposition, which is decisive in many pawn endgames.

A square, usually in enemy territory, that cannot be attacked by enemy pawns. Knights are especially strong on outposts.

A passed pawn far from the main pawn group, which can draw the enemy king away.

Chess played face to face with a physical board, often abbreviated OTB.

Giving one defending piece more jobs than it can handle, so that it must abandon one of them.

Defending an important point more times than immediately necessary, keeping defenders coordinated and flexible.

A pawn with no enemy pawn ahead on its own or either neighbouring file. It is a potential promotion threat.

A piece that normally advances one square and captures one square diagonally forward. Its initial move may advance two squares if both squares are empty.

A pawn move that challenges opposing pawns and changes or opens the structure.

Pawns linked diagonally so that each supports the next. The base is often a target.

An endgame with only kings and pawns remaining.

A group of pawns on adjacent files separated from other friendly pawns by empty files.

More pawns than the opponent on one part of the board, potentially creating a passed pawn.

Fewer pawns than the opponent on one part of the board.

A contest in which both sides advance pawns toward promotion, often making each tempo decisive.

A group of advancing pawns used to attack, often against the enemy king.

The arrangement of pawns, which shapes plans, weak squares and useful piece placement.

A rating estimate describing the strength of a player's results against a particular set of opponents.

A sequence of checks that can be repeated indefinitely. The draw normally follows from repetition or agreement, rather than a separate perpetual-check rule.

Portable Game Notation, the standard text format for recording chess games with their moves and headers.

A basic drawing rook-and-pawn setup in which the defending rook initially cuts off the attacking king from the sixth rank, then checks from behind at the right moment.

A rough comparison of fighting strength: pawn 1, knight or bishop about 3, rook 5 and queen 9. Position can matter more than these estimates.

An attack on a piece that cannot move without exposing a more valuable piece behind it.

One move by one player; a full move by White and Black consists of two plies.

A pawn that appears available but whose capture allows dangerous counterplay or a tactical loss.

Choosing moves for lasting features of the position rather than only immediate tactical gains.

Giving up material for lasting advantages such as strong squares, activity or a damaged enemy structure.

An attack launched before enough pieces are developed or the position is ready to support it.

An online interface feature that queues a move for your next turn, executing it if legal after the opponent's move.

The main continuation an engine currently considers best for both sides.

Replacing a pawn that reaches the last rank with a queen, rook, bishop or knight.

A move that prevents the opponent's plan before it starts, rather than pursuing your own.

A passed pawn defended by another pawn.

A piece that moves any distance along a rank, file or diagonal, without jumping over other pieces.

The half of the board on the a to d files.

A move that is neither a capture nor a check. A quiet threat can be the key to a combination.

A horizontal row of the board, numbered 1 to 8 from White's side.

A time control between blitz and classical. FIDE defines it as more than 10 and less than 60 minutes per player, adding 60 increments to the initial time; online labels can differ.

Capturing a piece immediately after it has captured one of yours.

A pin against a piece other than the king. Moving the pinned piece is legal but usually loses material.

Capturing or driving away a piece that protects an important target.

The openings a player prepares to use with White and Black.

A spare pawn move that can change whose turn it is in a critical position.

To concede the game. Players resign when they judge the position lost.

Limiting an opponent's available moves or plans.

1-0 means White won, 0-1 means Black won, and 1/2-1/2 means a draw. An asterisk indicates an unfinished or unknown result in PGN.

A piece that moves any distance along a rank or file. Rooks become especially effective when files open.

An endgame dominated by rooks and usually pawns. Rook activity and king placement are central.

Moving a rook up a rank and then sideways, often to join an attack on the king.

A pawn on the a- or h-file. Its edge position creates special drawing and promotion patterns.

A format in which every participant plays every other participant, once or more according to the event rules.

A fork of the opponent's king and queen, usually by a knight.

A shortcut for judging whether an unimpeded king can catch a freely advancing pawn. Account for whose turn it is and an available initial double step.

Deliberately giving up material for an attack, a positional gain or a forced sequence.

Opposing bishops that travel on the same colour squares and can challenge each other directly.

Standard Algebraic Notation, a move format such as Nf3, exd5 or O-O that uses position context.

Deliberately lowering a rating to obtain easier pairings or eligibility for a lower section.

The paper or approved electronic record used to write down moves during a game.

A file with no pawn of your own but at least one enemy pawn. It can provide a target for a rook.

Also known as Half-open file

An opening beginning 1.e4 with a reply other than 1...e5.

The rank just before promotion from a player's perspective. A rook there can attack pawns and restrict the enemy king.

An automatic draw after 75 moves by each player without a pawn move or capture. Checkmate on the final move takes precedence.

Positioning your king to obstruct the enemy king's route while approaching an objective.

An alternative to a main continuation, often less commonly played.

Reducing material through exchanges, often to ease defence or convert an advantage.

An event in which one player faces multiple opponents at separate boards.

An attack on a valuable piece that, when it moves, exposes a less valuable piece behind it to capture. The reverse of a pin.

Checkmate by a knight against a king that is completely surrounded by its own pieces.

The territory available for moving and coordinating pieces, often secured by advanced pawns.

The player to move has no legal move and is not in check. The game is a draw.

A defensive resource that forces or offers stalemate, often by giving away remaining movable material.

A relatively lasting benefit, such as extra material or a healthier pawn structure.

A time-control period in which all remaining moves must be completed within the available time.

Rescuing a poor or lost position through practical complications or an opponent's error.

A tournament format pairing players with similar scores without requiring everyone to play everyone else.

A standard opening position from which several typical plans or continuations begin.

A database of exact results for supported endgame positions. Its answer depends on the material covered and how the relevant draw rules are handled.

A unit of time in chess, equal to one move. Gaining a tempo means achieving something while making the opponent waste a move.

A position known to be drawn with correct play, even if it is difficult to defend in practice.

A position known to be winning with correct play, rather than merely offering practical chances.

Something a player intends to achieve on a later move, such as winning a piece or delivering mate.

A claimable draw when the same position occurs three times with the same side to move and the same possible moves, including relevant castling and en passant rights.

A method of ordering players with equal scores, such as an additional match or a score-based calculation.

The amount of thinking time allowed, including any increment, delay or additional time at a move milestone.

Having little time left to make the remaining required moves. Also called zeitnot.

The rule that if you deliberately touch one of your pieces you must move it, and if you touch an enemy piece you must capture it, as long as a legal move exists.

An exchange in which each side gives up material, often pieces of similar value.

Reaching the same position through a different order of moves.

Using a three-move king route to reach the same arrangement with the opponent to move.

The strategic idea of creating a second target so the defender cannot protect both comfortably.

Universal Chess Interface, a protocol used by chess interfaces to communicate with engines.

Promoting a pawn to a rook, bishop or knight instead of a queen.

A sequence of moves branching from a particular position.

A square that is difficult to defend, especially one that can no longer be protected by a pawn.

A repeating sequence of discovered checks and captures, often involving a rook and bishop.

Either side of the board: the queenside or kingside.

A bishop that cannot control a rook pawn's promotion square, which can prevent a win when the defending king reaches that corner.

An attack or defence that works through another piece, becoming active once that piece moves or is captured.

A German term for time trouble.

German for "compulsion to move". A position where any move worsens the mover's position, so they would rather pass if the rules allowed it.

German for "in-between move". An unexpected move, often a check or threat, played before making the expected recapture.

Also known as In-between move · Intermezzo