Chess glossary
Plain-language definitions for the terms you'll meet across ChessStride training. Not a legal document — just a quick reference. If a Tactics motif label is unfamiliar, it's explained here.
Board & notation
- Rank
- A horizontal row of the board, numbered 1 to 8.
- File
- A vertical column of the board, lettered a to h.
- Diagonal
- A slanting line of same-coloured squares that bishops and queens travel along.
- SAN (algebraic notation)
- The standard way to write moves: the piece letter plus the destination square, e.g. Nf3, Qxe5, O-O for castling.
- FEN
- A single line of text that describes an entire position — used to load a puzzle exactly.
- UCI move
- A move written as from-square then to-square, e.g. e2e4. The format engines use internally.
- Ply / half-move
- One move by one side. A full move is two plies (White then Black). Our tactics are measured in plies of solution depth.
Tactical motifs
- Fork
- One piece attacks two or more enemy targets at the same time.
- Pin
- A piece cannot move because doing so would expose a more valuable piece (or the king) behind it.
- Skewer
- Like a pin in reverse — a valuable piece is attacked and forced to move, exposing a lesser piece behind it.
- Discovered attack
- Moving one piece uncovers an attack from another piece behind it. A discovered check is the forcing version.
- Double check
- Two pieces give check at once. The king must move — nothing else can block or capture both.
- Deflection
- Forcing a defending piece away from a square or duty it was guarding.
- Decoy / attraction
- Luring an enemy piece (often the king) onto a square where it can be attacked.
- Removing the defender
- Capturing or chasing away the piece that guards a key square or target.
- Clearance / interference
- Vacating a square your own piece needs (clearance), or cutting the line between two enemy pieces (interference).
- Zwischenzug (in-between move)
- A surprising in-between move — usually a check or threat — inserted before the expected recapture.
- Sacrifice
- Giving up material on purpose to gain a bigger advantage, such as mate or a winning attack.
- Zugzwang
- A position where any move a player makes worsens their position — but they are obliged to move.
- Back-rank mate
- Checkmate delivered on the opponent’s first rank because their king is trapped behind its own pawns.
- Smothered mate
- A knight checkmate where the king is completely boxed in by its own pieces.
Strategy & structure
- Development
- Bringing your knights and bishops off the back rank into active play early in the game.
- Centre
- The four central squares (d4, e4, d5, e5). Controlling them gives pieces more scope.
- Tempo
- A single unit of time — one move. To "gain a tempo" is to make useful progress while forcing the opponent to react.
- Initiative
- The ability to make threats that the opponent must answer, keeping them on the defensive.
- Pawn structure
- The arrangement of pawns, which shapes long-term plans — including weaknesses like isolated, doubled or backward pawns.
- Outpost
- A square, usually protected by a pawn, where a knight or bishop can sit safely and cannot easily be driven away.
- Prophylaxis
- A quiet, preventive move that stops the opponent’s idea before pursuing your own.
Phases of the game
- Opening
- The first phase: developing pieces, castling and fighting for the centre.
- Middlegame
- The battle after development, where plans, attacks and tactics play out.
- Endgame
- The final phase with few pieces left, where king activity and pawn promotion decide the result.
- Repertoire
- The set of openings you choose to play with each colour.
Ratings & training terms
- Rating (Elo-style)
- A number that estimates strength. Beating tougher content raises it; missing easier content lowers it. ChessStride keeps separate puzzle, tactics and endgame ratings.
- Puzzle vs. tactic
- Puzzles are single sharp problems. Tactics in ChessStride are longer, graded combinations at least three of your own moves deep.
- Motif
- The tactical idea a position teaches — such as a fork or a pin. The Tactics trainer tracks your mastery per motif.
- Blunder / mistake / inaccuracy
- Grades of error by how much they change the evaluation — a blunder is a serious swing, an inaccuracy a small one.
- Evaluation (centipawns)
- The engine's score for a position in hundredths of a pawn; +1.00 means roughly a one-pawn advantage for White.
- Spaced repetition
- Revisiting a mistake or pattern at increasing intervals so it moves into long-term memory.
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