Best move - Chess glossary

Best move

Definition

In chess, the “best move” is the option that most improves or preserves a player’s objective result with correct play by both sides (win, draw, or loss). In practice this usually means the move that maximizes the engine evaluation for your side or, in tablebase positions, the move that provably leads to the optimal outcome. Sometimes multiple moves tie for “best” if they yield the same evaluation; other times there is a unique “only move” that avoids a serious disadvantage or immediate checkmate.

Because chess is complex, what counts as the best move can be considered from two angles: the theoretically best move (objective, under perfect play) and the practically best move (what gives the best chances against a human opponent given time, psychology, and risk). Modern analysis typically identifies the best move with the help of an Engine (engine eval measured in CP/Eval), or exactly in certain endgames via an Endgame tablebase.

How the term is used in chess

• Analysis and commentary: Annotators write “Best is …” to indicate the top choice; they may also note “Only move” when all alternatives fail.
• Puzzles: “Find the best move” tasks you to calculate forcing lines, tactical shots, or a strong Quiet move.
• Engines and tablebases: Analysis tools mark the engine’s top line with a principal variation and numerical eval; tablebases give exact results (mate in X, draw).
• Notation and jargon: You’ll see “BM” meaning “best move,” and contrasting phrases like Second best or “interesting but dubious.” Some “best” moves are dubbed a Computer move if they’re non-intuitive for humans.

Strategic and historical significance

Before strong computers, the best move was largely a matter of grandmaster consensus (“best by Book/Theory”). The engine era refined or overturned many assumptions—producing deep novelties (TN) and re-evaluating classic positions. Endgame perfection emerged with 6- and 7-man Endgame tablebases, which can prove the uniquely best move or show several moves are equally optimal.

In practical play, especially under Time trouble/Zeitnot, the “best move” often blends objective strength with Practical chances—for example, choosing a line that maintains pressure or simplifies to a technically won endgame rather than wading into razor-sharp complications.

Examples

Example 1: A clear best move (mate in one)

After a typical Scholar’s Mate blunder, there is a single, obviously best move that ends the game immediately.

Position after 1. e4 e5 2. Qh5 Nc6 3. Bc4 Nf6??. White’s best move is 4. Qxf7#, checkmate on f7.

Replay the moves up to the mating position:

• Why it’s best: It immediately delivers mate; any other move is strictly inferior.
• Lesson: When a forced checkmate exists, it defines the unique best move.

Example 2: Best by theory in a main line opening

In the Closed Ruy Lopez (a heavily analyzed opening), high-level practice and engines long favored 9...Na5 in the following position:

Position after 1. e4 e5 2. Nf3 Nc6 3. Bb5 a6 4. Ba4 Nf6 5. O-O Be7 6. Re1 b5 7. Bb3 d6 8. c3 O-O 9. h3. Black’s theoretical best move is often given as 9...Na5, planning ...Nxb3 and queenside expansion.

Replay to the position and show the intended best move:

• Why it’s considered best: It aligns with strategic goals (space on the queenside, exchanging White’s strong bishop) and generally equalizes Black’s game according to engines and top-level praxis.
• Note: “Best” can evolve as Home prep and engines improve.

Example 3: Tablebase best move (exact endgame play)

In certain rook-and-pawn endgames, the winning side must play a precise sequence known as Building a bridge (Lucena technique). Tablebases confirm the exact best moves and prove the win, while a single inaccuracy can throw away the advantage. In these endings, the “best move” is not just strong—it is mathematically optimal and often unique.

How to find the best move OTB

A practical checklist

• Generate candidate moves: Start with forcing moves (checks, captures, threats), then strong positional ideas (improve worst piece, create an Outpost, open an Open file).
• Calculate concrete lines: Look for tactics like Fork, Pin, Skewer, Zwischenzug; always consider opponent’s best replies.
• Evaluate the resulting positions: Use fundamentals—material, king safety, activity, pawn structure, space, initiative. Compare lines; don’t stop at the first move that looks good.
• Prophylaxis: Ask “What is my opponent’s idea?” and choose moves that limit counterplay.
• Blunder-check: Before playing your choice, quickly scan for tactics against your king and hanging pieces (LPDO / Loose pieces drop off).
• Time management: In Rapid, Blitz, or Bullet chess you may need the “practically best” move—good and safe—rather than an ultra-precise engine line.

Interesting facts and anecdotes

• Engines vs. humans: The “best move” often looks inhumanly calm—quiet consolidations or odd pawn moves that neutralize all counterplay. Such choices are sometimes labeled a Computer move.
• Kasparov vs. Deep Blue, 1997: The match highlighted how machine-selected best moves can surprise even the world champion, reshaping expectations for objective accuracy at the top level.
• Brilliancies and “best”: A move can be both the best and spectacular (earning a brilliancy or “!!”), but sometimes the best move is a modest Quiet move that seals a technical win.
• Best ≠ only: Many positions have several equivalent best moves; in sharp positions, there may be exactly one “only move” to avoid disaster.

Common misconceptions

• “Best move must be flashy.” Often the best move is prophylactic or consolidating, not a sacrifice.
• “Engines always agree.” Different engines, depths, and settings can change top choices; close evaluations may swap at higher depth.
• “Best move is always unique.” Ties are common; endgames and quiet positions often have several equally good moves.

Related terms and further study

• Computation: Engine, Engine eval, CP, Eval, Endgame tablebase, Tablebase
• Annotation and theory: Book, Book move, Theory, Novelty, TN, Prepared variation, Home prep
• Practice and psychology: Practical chances, Time trouble, Hope chess, Swindle
• Move quality spectrum: Second best, Inaccuracy, Mistake, Blunder, Howler
• Tactical tools: Fork, Pin, Skewer, X-ray, Discovered attack, Zwischenzug
• Endgames: Lucena position, Building a bridge, Fortress, Theoretical draw

Quick FAQ

Is the best move always the engine’s first line?

Practically, yes for objective analysis—especially at high depth. But in human play, the “practically best” move may be a simpler path that keeps winning chances with less risk.

Can there be more than one best move?

Yes. If multiple moves lead to the same evaluation (for example, all maintain a forced draw), they are equally best.

How do tablebases define best moves?

They give perfect play results. A best move is one that preserves the tablebase result (win/draw) in the fewest moves under optimal defense; any deviation changes the outcome or lengthens the win.