Make a move to see analysis here.
Fun facts about openings and rules will show up here as the game unfolds.
A reference to come back to, not something to memorize in one sitting. Click a section to expand it.
Control the center. The four central squares (d4, d5, e4, e5) give pieces the most reach from them — a knight on e4 attacks far more squares than a knight on a4. Moves like 1.e4 or 1.d4 stake a claim immediately; even if you don't occupy the center with a pawn, influencing it (e.g. a fianchettoed bishop on g2 eyeing d5) counts.
Develop your minor pieces before major ones. Get knights and bishops off the back rank and into the game before moving the queen far or shuffling rooks around — a piece sitting on its starting square is a piece doing nothing.
Castle early. King safety matters more in the opening than almost anything else. A king stuck in the center is exposed to open lines; castling tucks it away and connects your rooks in one move.
Don't move the same piece twice without a reason. Every "extra" move you spend re-shuffling one piece is a move your opponent gets to develop another. Only break this if it wins material, avoids a real threat, or gains a clear tempo.
Don't bring the queen out too early. A queen developed on move 2 or 3 is usually just a target — opponents develop their own pieces while chasing it away, gaining tempo for free.
Connect your rooks. Once your minor pieces are developed and you've castled, your rooks should be able to "see" each other along the back rank, with nothing (including your own queen) blocking the file between them.
Every move should have a purpose. Ask what a candidate move does for center control, development, or king safety. Moves that do none of these are usually premature.
Fork. One piece attacks two (or more) enemy pieces simultaneously, so the opponent can only save one. Knights are the classic forking piece because of their unusual movement, but any piece can fork.
Pin. A piece can't move (or shouldn't) because doing so would expose a more valuable piece behind it — most powerfully, a piece pinned to the king literally cannot move at all, since that would be an illegal move leaving the king in check.
Skewer. The mirror image of a pin: a valuable piece is attacked and forced to move, exposing a less valuable piece behind it to be captured.
Discovered attack. Moving one piece out of the way reveals an attack from a piece behind it — the moving piece can even do something else useful (like capture something itself) while the discovered piece does the real damage.
Double check. A special discovered attack where the moved piece and the revealed piece both give check at once. Since a single king move is the only way to escape two simultaneous checks, this is extremely forcing.
Deflection. Forcing a defending piece away from a square or task it's guarding — often with a sacrifice — so a follow-up move can exploit the now-undefended square.
Decoy / Attraction. Luring a piece (often the enemy king) onto a specific square where it becomes vulnerable to a further tactic, frequently via a sacrifice it's forced to accept.
Removing the defender. Capturing or deflecting the one piece that's protecting something, so it can be won on the next move.
Zwischenzug ("in-between move"). Instead of playing the expected recapture or reply, inserting a different forcing move first — a check or threat the opponent must answer — before completing the original exchange.
X-ray attack. An attack that operates "through" another piece along a shared line — similar in spirit to a pin or skewer, but describing the line of sight itself rather than the resulting tactic.
Clearance sacrifice. Giving up a piece purely to get it out of the way, opening a line or square for another piece to use.
Interference. Placing a piece between an enemy piece and what it's defending or attacking, cutting the line — usually sacrificially, since the interfering piece is often capturable.
Overloading. When one piece is responsible for defending two things at once, it can be "overloaded" — distracted into handling one job while the other falls.
Back rank weakness. A castled king boxed in by its own pawns, with no escape square on the back rank, is vulnerable to a rook or queen delivering mate along that rank if nothing can block or capture.
Smothered mate. A knight delivers checkmate to a king that has no legal moves because it's completely surrounded by its own pieces — one of the most famous mating patterns in chess.
Rough material values. Pawn = 1, Knight = 3, Bishop = 3, Rook = 5, Queen = 9. These are guidelines, not laws — a well-placed knight can outweigh a bad bishop, and initiative or king safety can be worth more than a pawn.
Piece activity often matters more than material count. A knight trapped in the corner is worth far less than its "3 points" suggest; a rook on an open file dominating the board is worth more than its "5."
Pawn structure.
• Isolated pawn — no friendly pawns on adjacent files to support it; often weak in the endgame, but can support active piece play in the middlegame.
• Doubled pawns — two pawns on the same file, usually from a capture; they control fewer squares between them than two separated pawns would.
• Passed pawn — no enemy pawns on its file or adjacent files ahead of it, so nothing can stop it from promoting except pieces.
• Backward pawn — stuck behind its neighbors, unable to advance safely, and often a long-term target.
Weak squares and outposts. A square that can never be attacked by an enemy pawn (because both neighboring enemy pawns are gone or can't advance there) makes an excellent permanent home for a knight — an "outpost."
The bishop pair. Keeping both bishops (rather than trading one off) is a small but real long-term advantage — together they cover both color complexes, something no single minor piece can do.
Good bishop vs. bad bishop. A bishop is "bad" when its own side's pawns are fixed on the same color square it moves on, blocking its own scope; "good" when its pawns are on the opposite color, leaving it open diagonals.
Open files and the 7th rank. A file with no pawns on it is a highway for a rook; a rook that reaches the opponent's 2nd rank (the "7th rank" from its own side) attacks pawns and can trap the enemy king.
Space. Pawns advanced further up the board cramp the opponent's pieces, giving them fewer safe squares — a persistent, hard-to-reverse advantage even without immediate tactics.
Prophylaxis. Before playing your own plan, ask what your opponent wants to do — and consider a move that prevents it, even if it doesn't advance your own position directly this move.
Initiative and tempo. A "tempo" is a single move's worth of time. Having the initiative means your opponent is reacting to your threats rather than making their own — often worth more than a pawn, at least temporarily.
The king becomes a strong piece. With most other pieces off the board, the danger of checkmate drops sharply — the king should actively join the fight, often heading toward the center, rather than staying tucked away.
Opposition. In king-and-pawn endgames, two kings facing each other with one square between them (on the same file, rank, or diagonal) puts whichever side is not forced to move at an advantage — that's "having the opposition."
The rule of the square. A quick way to check if a passed pawn can queen unassisted: draw an imaginary square from the pawn to the promotion square: if the defending king can step inside that square, it can catch the pawn; if not, the pawn queens.
Basic checkmates. King and queen vs. king, and king and rook vs. king, are worth drilling until automatic — the technique (driving the enemy king to the edge, then the corner) recurs constantly, and failing to convert a won endgame is a common, avoidable way to throw away a game.
Lucena and Philidor positions. Two of the most important rook-endgame patterns: the Lucena position is a winning technique for the side with an extra pawn near promotion ("building a bridge" with the rook); the Philidor position is a drawing technique for the defending side, keeping the rook on the 3rd rank until the pawn advances, then switching to checks from behind.
Zugzwang shows up constantly in endgames. With few pieces left, "waiting" moves become impossible — often, whoever is forced to move first is forced to make their position worse.
When to trade pieces. If you're ahead in material, trading pieces (not pawns) simplifies toward a won endgame and reduces your opponent's swindling chances. If you're behind, avoid trades and keep pieces on the board for practical complications.
Tactics training has the highest return for most improving players. Pattern recognition for forks, pins, and mating nets builds faster than almost any other study method — which is exactly what the Puzzles tab here is for.
Review your own games, especially losses. Find the exact move where the evaluation swung and ask what you missed at that moment — this is what the Move Coach is built to help with, move by move, as you play.
Don't over-study openings early on. Learning the ideas behind an opening (why the pieces go where they go) matters far more at a casual level than memorizing long move sequences. Depth comes naturally with repetition.
Play slower time controls while learning. Blitz is fun, but it doesn't build the habit of calculating before moving — that habit is easiest to build with time to actually think.