The Repertoire — Build Once, Never Rebuild

The five ideas

• The whole opening is one plan: re-route the knight Nb1→d2→f1→g3, tuck the bishop to b3, rook to e1, then break with d3–d4.
• h3 before d4, always. It prevents …Bg4 pinning the knight that has to defend d4.
• Never trade the light-squared bishop. The c4–b3–a2 diagonal aimed at f7 is your whole attacking asset. Retreat it, don't exchange it.
• After d4: if …exd4 cxd4, you have the classical big centre. If Black keeps the tension, improve with a4/a5 or Nf5.
• The attack comes later and for free — Nf5, Qd2, Nh2–g4, or clamp with d4–d5 and expand with c4/b4. Play where his pieces aren't.

Traps you must know

• 3…Nd4 (Blackburne–Shilling). The greedy 4.Nxe5? invites 4…Qg5! and then 5.Nxf7?? Qxg2 6.Rf1 Qxe4+ 7.Be2 Nf3# — a genuine mate, and the whole reason this trap exists. (Pedantic but useful: 4.Nxe5 itself is only dubious — 5.Bxf7+! keeps White alive. It's the second grab, 5.Nxf7, that loses. Simplest is not to enter it at all.)
  Just play 4.Nxd4! exd4 5.c3. Black's best is 5…d5! (6.exd5 Qe7+ 7.Kf1), not 5…dxc3 6.Nxc3 which hands you a huge development lead.
• 3…Bc5 4.c3 Qg5?? → 5.Nxg5 and you simply win the queen. Your knight on f3 already covers g5 — this is the mirror image of the Blackburne trap above, and knowing why the two positions differ is worth more than memorising either.
• 3…Nf6 4.d3 Ng4? (going for f2) → 5.O-O! and f2 is defended by the rook; then h3 kicks it. Never allow …Nxf2 while your rook is still on h1.

The annoying reply, and the one-move answer

3…Nf6 (Two Knights, heading for complications). Answer: 4.d3. One move, kills every 4.Ng5 theory branch, and transposes straight back into your setup. Also 3…Be7 (Hungarian) → 4.d4! exd4 5.Nxd4 and you have a free centre.

If Black plays 2…Nf6:

If Black plays 2…d5:

The ideas

• You are playing for a d4/e5 space centre or a d4 isolani. Black's two replies only choose which one you get.
• The 2…d5 line is a Scandinavian with colours reversed — your Caro-Kann knowledge of chasing an exposed queen transfers directly.
• Isolani plan: Bd3, Re1, Qe2, Rad1, then either the d4–d5 break or Ne5/Ng5 kingside pressure.
• Everything else — 2…e6, 2…g6, 2…d6, 2…Nc6 — just play 3.d4 and you're in the same structures. This is why the Alapin is ~15–20 positions total instead of six separate anti-Sicilians.

The annoying reply

2…d5 3.exd5 Qxd5 4.d4 Nf6 5.Nf3 Bg4 (pin). Don't fight it: 6.Be2 e6 7.h3 Bh5 8.O-O Nc6 9.Be3, or simply 6.Be2 and Nc3 gaining tempo on the queen.

vs the French:

vs the Caro-Kann (Short System):

The ideas

• The d4–e5 chain gives you space. Black attacks its base (d4) with …c5 and …Qb6/…Nc6. Your entire job is to hold d4 — c3, Be3, Nf3, sometimes Na3–c2 — and not panic.
• Once d4 is secure, the win comes from kingside space: Nh4 hitting the f5-bishop, f2–f4–f5, or h4–h5.
• Trade Black's good bishop. In the Caro that's the one on f5 — it's his only comfortable piece.
• Keep the c3 pawn and have Bd2/Nc3 ready so …Bb4+ tricks never bite.

Traps

• French: 5…Qb6 — play 6.Be2, not 6.Bd3. Not because 6.Bd3 is bad: it is the Milner-Barry Gambit, a perfectly respectable named line where White deliberately offers d4 (6…cxd4 7.cxd4 Nxd4 8.Nxd4 Qxd4 9.Bb5+! with a dangerous initiative). It's a real opening with real theory, and you have a couple of hours a week. 6.Be2 needs none.
• Caro: 3…Bf5 4.Bd3?! Bxd3 5.Qxd3 e6 6.Nc3 Qb6! hits b2 and d4. Play 4.Nf3 first.
• Caro 3…c5 (immediate strike): 4.c3 Nc6 5.Nf3 — treat it as a French Advance where his bishop happens to be outside. Hold d4, Be2/Be3/O-O.

Move order matters: play 7…Nd7 before …e6. (7…e6 is playable, but 8.Ne5 gives White a pull for free and there's no reason to allow it.) Note that 11.Bf4 is as much "the" main line as 11.Bd2 — both are standard; your plan is unchanged either way.

The five ideas

• The point of 1…c6 is to play …d5 and still get the c8-bishop outside the pawn chain. It is the French with the French's one problem solved.
• After the light bishops come off you have a weakness-free structure: c6/e6/f7/g7/h6 against d4. There is nothing for him to attack.
• Your break is …c5 (sometimes …e5). Prepare with …Qc7 and rooks to d8/c8.
• White usually castles long. You castle short and play …c5, …b5, …a5, …Rb8 — the queenside is where your attack lives.
• After …Ngf6, if he trades Nxf6+, recapture with the knight (…Nxf6) to keep the structure clean.

The one thing you must never get wrong

h4 → …h6, always. And understand why, because the reason is the move: …h6 manufactures the h7 square for your g6-bishop. White's whole idea is h4–h5, kicking that bishop. Without …h6 first, it has nowhere good to go (h7 is still occupied by your own pawn, and h5/f5/e4 all run into trouble). Play …h6, and when h5 comes you retreat …Bh7 in comfort — which is exactly what happens on moves 6 and 8 of the main line.

The alternative 6…h5?! is playable but chronically weakening — after the light-squared bishops come off, h5 is a permanent target. Just play …h6.

Every branch he can take — one line each

Panov trap: don't grab with 6…dxc4?! 7.Bxc4 — you just hand him development.

That's the Capablanca freeing manoeuvre — the model game for the whole opening.

The five ideas

• The setup is the opening: …d5, …e6, …Nf6, …Be7, …O-O. Learn the shape, not the moves. It is good against literally every White system — Queen's Gambit, London, Colle, Torre, Jobava, Catalan.
• Timing of …dxc4: only capture when it gains a tempo on his bishop — i.e. after he's played Bd3. You convert one tempo into the freeing …Nd5.
• The two freeing breaks are …c5 and …e5. …Nd5 (trading a knight pair and the g5-bishop) is what enables …e5.
• Never move the c8-bishop early. It gets solved by the …dxc4/…Nd5/…e5 plan, or goes to b7 after …b6. Patience is the actual skill this opening teaches — which is why it's good for you.
• If he plays the Exchange (cxd5 exd5) he'll launch the minority attack (Rb1, b4–b5). Counter on the kingside: …Ne4, …Bd6, …f5, …Qf6.

Traps

• The Elephant Trap — worth knowing in both directions: 1.d4 d5 2.c4 e6 3.Nc3 Nf6 4.Bg5 Nbd7 5.cxd5 exd5 6.Nxd5?? Nxd5! 7.Bxd8 Bb4+ 8.Qd2 Bxd2+ 9.Kxd2 Kxd8 and Black is a piece up.
• …dxc4 too early: 6…dxc4?! 7.Bxc4 and he got the bishop to c4 in one move instead of two. Wait for Bd3.
• Don't play …b5 while the a8–h1 diagonal is open and your bishop is still on c8 — watch for Nxb5! and Bxf6 with Qf3/Qb3 hitting b7 and f7 at once.

Every White system, one line each

…Nc6 comes first — this is not optional. Play 2…g6?? immediately and 3.Qxe5+ forks your king and the h8-rook. Defend e5 first, then block the diagonal.
Never …Nh6 (Bxh6 wrecks your kingside). Never defend passively with …Qe7 if you can develop instead.

Punishing the greedy tries (both instead of 5.Ne2)

• 5.Qb3 Nd4! 6.Bxf7+ Ke7 7.Qc4 b5! — the queen was the only defender of the bishop; it's overloaded and you win the piece back with a winning game.
• 5.g4 Nd4! 6.Qd1 (or 6.Qd3 d5!) 6…d5! — rip the centre open against an uncastleable king.

A pawn down, but a large lead in development and full compensation (11.d4 exd3 12.Nxd3 Qc7 13.b3).

Never 5…Nxd5? → 6.Nxf7! Kxf7 7.Qf3+ Ke6 8.Nc3 and your king is dragged into the open. Engines say Black can technically survive; humans do not. Treat it as losing.

The simpler answers: as Black, play 3…Bc5 (Giuoco Piano) and it can't happen. As White, play 4.d3 and stay in your own system. And of course, with the Caro-Kann you never see it at all.

The guiding principle: "no short castle, no checkmate." Keep the king in the centre or castle long. You're a clean pawn up with a better structure — he has doubled c-pawns and no centre.

• 6…Ng4 7.Bxg4 Qh4 8.g3 Qxg4 9.Qxg4 Bxg4 10.Be3 — winning endgame, extra pawn.
• 6…Qd4 7.O-O — f2 is safe. Then c3, d4, e5.

The mate to avoid: 5.d3 Bc5 6.Bg5?? Nxe4! 7.Bxd8 Bxf2+ 8.Ke2 Bg4#. Do not play Bg5. Do not play Nc3 early. Play Be2.

8.Rb3 is the old main line and is fine, but 8.Nd5! (Bücker) is close to a theoretical refutation — Black is forced into 8…Bxd2+ 9.Qxd2 Qxa2 10.Rd1 Kd8 and is simply lost.

The mate you must not walk into: 6.Bc3?? Bb4! 7.Qd2 Bxc3 8.Qxc3 Qc1#

One rule: block the check with the BISHOP (5.Bd2), then develop the KNIGHT (6.Nc3). Never 6.Bc3. After that you're a clean pawn up with his queen stranded, and almost anything wins.

Halloween: 1.e4 e5 2.Nf3 Nc6 3.Nc3 Nf6 4.Nxe5 Nxe5 5.d4 Nc6! 6.d5 Bb4!
then 7.dxc6 Nxe4 8.Qd4 Qe7 9.Qxg7 Nxc3+ 10.Be3 Nd5+ 11.c3 Rf8 12.cxb4 Nxe3 13.fxe3 Qxb4+ — material is level here, but Black's position is close to winning (this is Piński's line; Kaufman confirms 5…Nc6 over the riskier 5…Ng6).

If you can't recall the line, the human rule works: give back the extra piece for development, get castled, trade queens. His whole gambit is one wave — survive it and the extra material wins.

Damiano (2…f6??): 3.Nxe5! fxe5 4.Qh5+ Ke7 5.Qxe5+ Kf7 6.Bc4+ Kg6 7.Qf5+ Kh6 8.d4+ g5 9.h4 — White is a knight for two pawns down and completely winning anyway: the black king is stranded on h6 with no shelter. (Engines find mate here, but not by force in the next few moves — e.g. 9…Kg7 10.Qf7+ Kh6 11.hxg5+.)

The universal defence to every early f7 attack (Bc4 + Qf3 + Ng5 batteries): block with …e6 or …Nf6, answer Qh5 with …g6, bring a piece to defend f7. Never move your f-pawn. Never play …Nh6.