Every term,
plainly.

The standard way to write chess moves: piece letter, destination square, and markers for captures, checks, castling and promotion. For example, Nf3, exd5, O-O and e8=Q+.

A comment attached to a move, position or game. Annotations can be prose, symbols such as ! and ?, or engine evaluations.

The official responsible for running a tournament: pairings, clock disputes, rule enforcement and results.

1. e4 Nf6. Black invites White to advance pawns and then targets the overextended centre.

A White system against the Sicilian that avoids the main Open Sicilian lines, such as the Alapin or Grand Prix Attack.

A position that is better for one side, whether through material, structure, space, king safety or piece activity.

Direct play against the opponent’s king or weaknesses, usually requiring concentration of pieces on a target.

A pin against the king. The pinned piece cannot legally move at all.

A mating pattern using a knight and rook, with the knight protecting the rook on a corner square.

A mating pattern with a knight and rook, usually on the edge of the board, where the rook controls the escape file.

A tournament format where players join at any time and are paired repeatedly, often with a fixed duration.

A decisive tiebreak game where Black wins the match on a draw, compensating for White’s first-move advantage.

A score estimating how close a player’s moves were to the engine’s best choices across a game.

Application Programming Interface: a documented way for programs to read or change data on ChessUrge.

A serious mistake that turns a good or equal position into a lost one. Engine reviews usually mark it with ??.

A family of openings with ...c5 and ...e6 against d4, often leading to a queenside pawn majority for Black.

1. e4 e5 2. Nf3 Nc6 3. Bb5 Nf6. Black attacks e4 and invites the exchange on c6, leading to the famous Berlin Wall endgame.

A move that follows established opening theory rather than independent calculation.

A pawn that is behind its neighbouring pawns and cannot be supported by another pawn. It often becomes a target.

A bishop blocked by its own pawns or restricted to squares of one colour, reducing its activity.

Two or more pieces aligned on the same file, rank or diagonal, usually queen and bishop or queen and rook.

Having both bishops while the opponent has a bishop and knight. The pair is especially strong in open positions.

A pawn move that challenges the opponent’s structure and opens lines, such as ...c5 or ...e5.

Checkmate on the first or eighth rank when the king is trapped behind its own pawns.

A mate delivered by two bishops on adjacent diagonals, often after clearing the long diagonals.

A pawn sacrifice that opens a path for another pawn to promote.

A tiebreak that sums the scores of a player’s opponents. Beating stronger opposition raises the tiebreak.

A round in which a player does not play but usually receives a point or half-point, common in Swiss events with odd entries.

Fast chess, usually with three to five minutes per player, often with an increment.

Very fast chess, typically under three minutes per player.

A king-and-rook move that puts the king on g1/c1 and the rook on f1/d1. The king may not pass through check, and neither piece may have moved.

A position in which the king is attacked. The side in check must escape, block or capture the attacker.

A position in which the king is in check and there is no legal way to escape. The game ends immediately.

A two-dial timer that allocates thinking time to each player. Digital clocks also handle increment and delay.

The central squares d4, d5, e4 and e5. Control of the centre gives pieces more space and mobility.

An opening with locked or semi-locked pawn chains, typically beginning with 1. d4 d5.

1. e4 c6. Black prepares ...d5 while keeping a healthy pawn structure and a route for the light-squared bishop.

1. d4 Nf6 2. c4 e6 3. g3. White fianchettoes the bishop and applies long-diagonal pressure.

A move worth calculating in a given position, usually selected before deeper analysis.

Non-material assets — activity, initiative, structure or king safety — that balance sacrificed material.

Pawns on adjacent files that can protect each other. Connected passed pawns are especially powerful.

A player’s active response to the opponent’s plan, often creating threats elsewhere instead of defending passively.

A moment where the evaluation can swing sharply and accurate calculation matters most.

A forced sequence of moves, often involving a sacrifice, that achieves a concrete result such as mate or material gain.

Moving a piece out of the way so another piece can use the square or line it occupied.

The technique of turning a winning advantage into a win without allowing counterplay.

Slow chess with long time controls, often 90 minutes or more per player.

Chess played over days or longer, historically by post and now online.

Confirming attendance before a tournament or round so organisers can pair active players only.

One hundredth of a pawn. An evaluation of +0.50 means White is half a pawn better.

Comma-separated values: a plain-text table format used for tournament standings and data export.

Stored results reused to save work. ChessUrge caches engine analysis and served pages to respond faster.

The 32 squares that are dark-coloured on a standard board. a1 is dark; h1 is light.

A game with no winner. Draws occur by agreement, stalemate, repetition, the fifty-move rule or insufficient material.

Bringing pieces from their starting squares into active positions. Quick development is a core opening principle.

1. d4 f5. Black stakes a claim on the kingside and e4, often leading to unbalanced positions.

Two pawns of the same colour on the same file. They can be strong in some structures but are usually less mobile.

Luring an enemy piece to a square where it becomes vulnerable or can be deflected from a defensive duty.

Forcing a defending piece away from the square or line it is protecting.

Moving one piece to unleash an attack from a second piece behind it.

A discovered attack that gives check, letting the moving piece create an additional threat.

One move that creates two threats at once, so the opponent can answer only one.

A check delivered by two pieces simultaneously. The king must move; blocking or capturing one attacker is not enough.

A countdown before a player’s main clock starts on each move, used to reduce time scrambles.

How many plies ahead an engine searches. Greater depth usually means stronger analysis but takes longer.

A special pawn capture: if a pawn advances two squares and lands beside an enemy pawn, that enemy pawn may capture it as if it had moved one square.

Encyclopaedia of Chess Openings: a classification system that assigns codes A00–E99 to opening lines.

1. c4. White controls d5 from the flank and often transposes into reversed Sicilian or Queen’s Gambit structures.

Trading a minor piece for a rook, or simply trading pieces. “Winning the exchange” means gaining a rook for a minor piece.

Giving up a rook for a minor piece in return for structural or positional compensation.

The final phase of the game, when few pieces remain and king activity and pawn promotion become central.

A rating system developed by Arpad Elo. Expected score is derived from the rating difference between two players.

A computer program that calculates chess moves. ChessUrge runs Stockfish for analysis and bot play.

An engine’s assessment of a position, usually in centipawns, with positive values favouring White.

Forsyth-Edwards Notation: a one-line description of a chess position including pieces, side to move, castling rights, en passant target and move counters.

The International Chess Federation, the governing body for international chess, ratings and title regulations.

A player may claim a draw if fifty consecutive moves by each side have been made without a pawn move or capture.

A vertical column of eight squares, labelled a through h.

The indicator that a player’s clock has run out. In a game with insufficient mating material, flagging may still be a draw.

Developing a bishop to b2 or g2 behind a pawn on b3 or g3, aiming it at the long diagonal.

An opening that begins with a wing pawn move such as 1. c4 or 1. Nf3 rather than a central pawn move.

1. e4 e6. Black builds a solid pawn chain and challenges the centre with ...d5, at the cost of a passive light-squared bishop.

1. e4 e5 2. Nf3 Nc6 3. Nc3 Nf6. A symmetrical, classical opening with both sides developing naturally.

One piece attacks two or more enemy pieces at once. Knights are especially effective forkers.

A defensive setup that cannot be broken down even with a material disadvantage, often leading to a draw.

A loss awarded without play, for example when a player does not arrive or violates the rules.

The principle that games are decided by skill, not engine assistance, collusion or harassment.

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

1. d4 Nf6 2. c4 g6 3. Nc3 d5. Black strikes at the centre immediately and relies on piece pressure against White’s big pawn centre.

A bishop that has open diagonals and is not blocked by its own pawns.

The sacrificial Bxh7+ pattern against a castled king, often followed by Ng5 and a mating attack.

A mating pattern using queen and bishop against a castled king, often with a sacrifice on h7 or g7.

A square that cannot be defended by a pawn. Pieces, especially knights, can occupy holes safely.

An undefended piece that can be captured. Leaving a piece hanging is a common blunder.

A move that breaks the rules, such as exposing your own king to check or moving a pinned piece.

1. e4 e5 2. Nf3 Nc6 3. Bc4. White develops quickly and aims at f7; the Giuoco Piano and Two Knights Defence are main branches.

The ability to dictate play and force the opponent to respond, even without a material advantage.

A pawn with no friendly pawns on adjacent files. It cannot be defended by a pawn and can become a target.

Placing a piece on a line between two enemy pieces to disrupt their coordination.

Time added to a player’s clock after each move, such as five seconds per move.

iCalendar format: a standard text file used to subscribe to tournament and club-event calendars.

The half of the board from the e-file to the h-file. Castling short places the king on the kingside.

Keeping the king protected, usually by castling and avoiding unnecessary pawn moves in front of it.

1. d4 Nf6 2. c4 g6. Black allows White a broad centre, then attacks it with ...e5 and piece pressure.

A square whose occupation allows a pawn to promote or a king to penetrate the defence.

A bracket format where the loser of each match is eliminated.

A move permitted by the rules in the current position.

The 32 squares that are light-coloured on a standard board. h1 is light; a1 is dark.

A flexible White setup with d4, Nf3, Bf4, e3 and c3, aiming for a safe structure and a kingside initiative.

A queen sacrifice followed by a knight mate, named after the 18th-century player who popularised it.

A classic rook-and-pawn endgame where the stronger side builds a bridge to shelter the king and promote.

A queen or rook. Major pieces are more valuable than minor pieces and usually dominate the endgame.

A bishop or knight. Minor pieces are worth roughly three pawns, though their relative value depends on the position.

The most respected or most frequently played continuation in a given opening.

A sharp line in the Ruy López where Black sacrifices a pawn for a strong kingside attack.

Advancing a smaller group of pawns against a larger pawn majority to create weaknesses on the opponent’s side.

A configuration of pieces that covers the king’s escapes and delivers checkmate despite defensive resources.

A recurring tactical pattern, such as a fork, pin, skewer or discovered attack.

The minimum pieces needed to force checkmate. King and two knights cannot force mate; king and rook can.

A setting that shows several best engine lines instead of only the top move.

Any system for recording chess moves. Algebraic notation is the modern standard; descriptive notation was common before it.

1. d4 Nf6 2. c4 e6 3. Nc3 Bb4. Black pins the knight and fights for control of e4.

A move in a known opening that has not appeared in published games or databases before.

One position evaluated by an engine. Node counts measure how much work an analysis performed.

Numeric Annotation Glyph: a standard PGN code for symbols such as !, ?, !? or a checkmate annotation.

The first phase of the game, roughly the first 10–20 moves, where players develop pieces, contest the centre and decide on a plan.

An opening that begins 1. e4 e5, leading to open lines and often rapid piece play.

A tempting but unsound line that punishes a natural-looking move. Traps are useful training but dangerous as a repertoire.

A square deep in enemy territory, protected by a pawn and difficult for enemy pawns to attack. Knights love outposts.

Advancing pawns or pieces too far without sufficient support, creating weaknesses behind them.

Giving a defending piece more jobs than it can handle, so one threat breaks through.

A king duel where one king faces the other with one square between them, forcing the opponent to yield ground.

A passed pawn on the wing, far from the main pawn battle. It can distract the enemy king and decide the game.

Portable Game Notation: a plain-text format for storing chess games, including headers, moves and comments. ChessUrge imports and exports PGN.

Any of the six chess unit types: king, queen, rook, bishop, knight or pawn. “Piece” sometimes means everything except pawns.

One half-move. 1. e4 is one ply; 1. e4 e5 is two plies. Engines often report depth in plies.

When a pawn reaches the eighth rank it must become a queen, rook, bishop or knight. Promotion to a piece other than a queen is an underpromotion.

1. e4 d6. Black allows White to build a centre, then attacks it with ...Nf6, ...g6 and ...c5.

A variation, especially in the Sicilian, where one side grabs a seemingly free pawn and must survive a dangerous initiative.

A diagonal line of pawns protecting one another. The base of the chain is often the key target.

A group of connected pawns separated from other friendly pawns by at least one file.

Having more pawns than the opponent on one wing, usually an asset in the endgame.

The permanent arrangement of pawns. Structure determines the squares, plans and long-term weaknesses in a position.

A concrete sequence of ideas aimed at a target, such as improving a piece, opening a file or attacking a weakness.

Play based on long-term features — structure, space, activity and weaknesses — rather than immediate tactics.

Preventive play that stops the opponent’s plan before pursuing your own.

A piece is attacked along a line and cannot move without exposing a more valuable piece behind it.

A repeated series of checks that cannot be escaped, usually forcing a draw by repetition.

A drawing method in rook-and-pawn endgames where the defender keeps the rook on the third rank and checks from behind.

A pawn with no enemy pawns on its file or adjacent files, giving it a clear path toward promotion.

A passed pawn defended by another pawn. It is especially strong because the king alone cannot stop it.

A position where both sides push passed pawns toward promotion, often decided by one tempo.

The rating a player would need to have produced their score against a given field.

The assignment of opponents for a round.

A separate rating that rises and falls as you solve or miss tactical puzzles.

A timed puzzle mode where each correct answer adds time and difficulty increases.

Progressive Web App: a website that can be installed on a device and opened like a native app.

The half of the board from the a-file to the d-file. Castling long places the king on the queenside.

1. d4 d5 2. c4. White offers the c-pawn to gain central control; Black can accept, decline or enter a Slav structure.

A horizontal row of eight squares, numbered 1 through 8 from White’s side.

Conceding the game because the position is hopeless. A resignation counts as a loss for the player who resigns.

1. e4 e5 2. Nf3 Nc6 3. Bb5. White pressures the knight defending e5; one of the oldest and richest openings.

Moving a rook to the third or fourth rank to transfer it to another file or support an attack.

A pin against a valuable piece other than the king. The pinned piece may still move if the gain justifies the loss.

A tournament where every player plays every other player once.

A numerical estimate of playing strength. ChessUrge uses separate ratings for games and puzzles.

Chess with a longer time control than blitz, commonly 10–25 minutes per player.

A prepared set of opening lines chosen for one colour.

A position in which the side to move has no legal move and is not in check. The game is drawn.

An opening where White plays 1. e4 and Black replies with something other than 1... e5.

1. e4 c5. Black fights for the centre asymmetrically, often accepting a spatial disadvantage for counterplay on the queenside.

1. e4 d5. Black challenges the centre immediately and usually recaptures with the queen after 2. exd5 Qxd5.

1. d4 d5 2. c4 c6. Black supports d5 with a pawn while keeping the bishop’s diagonal open.

1. e4 e5 2. Nf3 Nc6 3. d4. White opens the centre early and accepts a symmetrical pawn structure.

The amount of territory controlled by a player’s pieces and pawns. More space usually means easier manoeuvring.

A position where both sides have equivalent structures and pieces. The side that first breaks symmetry often gains the initiative.

Giving up material deliberately for a concrete tactical or positional benefit.

An attack along a line that forces a valuable piece to move, exposing a less valuable piece behind it.

A checkmate delivered by a knight when the enemy king is surrounded by its own pieces.

A practical trick played from a worse or lost position to confuse the opponent into a mistake.

A popular tablebase format used by engines and analysis tools for exact endgame evaluation.

A tournament format where players are paired against opponents with similar scores, usually over a fixed number of rounds.

A tiebreak that adds the full score of defeated opponents and half the score of drawn opponents.

A player’s initial placement in a bracket or pairing system, usually based on rating.

A leading open-source chess engine. ChessUrge uses Stockfish 19 for deep analysis and its bots.

A saved collection of positions with notes, used for opening prep, endgame training or lessons.

One unit of time, usually one move. Gaining a tempo means saving or gaining a move; losing a tempo means wasting one.

A draw claim available when the same position, with the same side to move, castling rights and en passant rights, occurs three times.

The amount of time each player receives for the game, often written as base time plus increment, such as 10+5.

The rule that a player who deliberately touches a piece must move it if a legal move exists. It applies in over-the-board chess.

Reaching the same position through a different move order. Transpositions are central to opening preparation.

A position where pieces or pawns are attacking each other but neither side has captured, keeping options open.

A short forced manoeuvre that exploits a specific weakness or tactical motif.

A king manoeuvre that returns to the same square in three moves, losing a tempo to put the opponent in zugzwang.

A database of perfect endgame results. ChessUrge can query tablebases for positions with few pieces.

A position known to be drawn with correct play, regardless of practical complications.

Having very little time left on the clock, which increases the chance of mistakes.

A secondary score used to separate players on equal points, such as Buchholz or head-to-head.

Promoting a pawn to a rook, bishop or knight instead of a queen, usually to avoid stalemate or deliver a specific tactic.

A branch of an opening or game tree. Variations are often named after players or places.

1. e4 e5 2. Nc3. White prepares f4 and a kingside attack without committing the knight to f3.

A pawn or square that is difficult to defend and can be attacked by the opponent.

A repeated discovered-check pattern in which a rook and bishop strip the enemy king of material.

A rook pawn that cannot promote because the defending king reaches the corner. It often turns a winning position into a draw.

A move that changes nothing important, used to put the opponent in zugzwang.

A piece attacks through an enemy piece to a target behind it, often after the front piece moves.

An in-between move played before the expected recapture or continuation, often changing the position decisively.

A situation where any move worsens the position, but the player must move.