Opening theory/line knowledge requirements

Is there a website out there that clarifies the amount of opening theory that needs to be memorized in order to play it effectively? (I.e.- a ranking of greatest memorization necessary versus the least. Have heard Sicilian is crazy, etc.). I am looking at a few different openings but don't want to have to memorize a ton of lines. Any direction or input would be greatly appreciated.

Here is my own set of personal recommendations for memorization that I've posted before. Opinions may vary, however. Keep in mind that most of these many variations cannot appear as soon as you select a fixed set for yourself, since your own personal line will trim the move tree considerably.

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Sqod's recommended bare minimum opening moves memorization for club/beginning levels.

These recommended move sequences do the following:

o contain only essential moves to know.

o avoid the most common early opening traps.

o develop the best knight first, in order to avoid early material loss or poor position.

o exploit the most common mistakes.

o leave off at a move where most natural continations will suffice.

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e-pawn openings

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double e-pawn openings

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Bishop's Opening

1. e4 e5

2. Bc4 {Bishop's Opening.} Nf6 {Berlin Defense.}

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Center Game

(a) Paulsen Attack

1. e4 e5

2. d4 exd4 {Center Game.}

3. Qxd4 Nc6

4. Qe3 {Paulsen Attack.}

(b) Danish Gambit

1. e4 e5

2. d4 exd4 {Center Game.}

3. c3 {Danish Gambit.} d5 {Soerensen Defense.}

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Damiano's Defense

1. e4 e5

2. Nf3 f6?! {Damiano's Defense.}

3. Nxe5 fxe5??

4. Qh5+ {White wins.}

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Elephant Gambit

1. e4 e5

2. Nf3 d5 {Elephant Gambit.}

3. exd5 e4

4. Qe2 Nf6

5. Nc3 Be7

6. Nxe4

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Four Knights Game

(Almost all reasonable continuations will suffice.)

Warning for Black: Don't steal White's e4-pawn before you're castled. (Re1 can pin your queen or knight against your king and win that piece.)

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King's Gambit

(Too heavily dependent on specific moves to summarize easily.)

Warning for White: Don't play fxe5. (That will allow Black to win with an attack starting with ...Qh4+.)

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Latvian Counter-gambit

1. e4 e5

2. Nf3 f5 {Latvian Counter-gambit.}

3. Nxe5 Qf6

4. d4 d6

5. Nc4

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Patzer Opening

1. e4 e5

2. Qh5 {Patzer Opening.} Nc6

3. Bc4 g6

4. Qf3 Nf6

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Petrov's Defense

(a) Main Line

1. e4 e5

2. Nf3 Nf6 {Petrov's Defense.}

3. Nxe5 d6

4. Nf3 {Main Line.} Nxe4

(b) Modern Attack

1. e4 e5

2. Nf3 Nf6 {Petrov's Defense.}

3. d4 {Modern Attack.} Nxe4 {Symmetrical Variation.}

(c) Petrov Three Knights Game

1. e4 e5

2. Nf3 Nf6 {Petrov's Defense.}

3. Nc3 {Petrov Three Knights Game.} Bb4

4. Nxe5 O-O

5. Be2 Re8

6. Nd3

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Philidor's Defense

(a) Exchange Variation

1. e4 e5

2. Nf3 d6 {Philidor's Defense.}

3. d4 exd4 {Exchange Variation.}

(b) Hanham Variation

1. e4 e5

2. Nf3 d6 {Philidor's Defense.}

3. d4 Nd7 {Hanham Variation.}

4. Bc4

(c)

1. e4 e5

2. Nf3 d6 {Philidor's Defense.}

3. d4 Bg4?!

4. dxe5 Bxf3

5. Qxf3 dxe5

6. Bc4 Nf6

7. Qb3 {White wins.}

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Ruy Lopez

(Too heavily dependent on specific moves to summarize easily.)

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Scotch Opening

1. e4 e5

2. Nf3 Nc6

3. d4 {Scotch Opening.} exd4

4. Nxd4

Warning for Black: Don't play ...Nxd4. (That will allow White to centralize his queen.)

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other e-pawn openings

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Alekhine's Defense

(Almost all reasonable continuations will suffice.)

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Caro-Kann Defense

1. e4 c6 {Caro-Kann Defense.}

2. d4 d5

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Fred

1. e4 f5 {Fred.}

2. exf5 Nf6

3. d4 d5

4. Bd3 Nc6

5. c3

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French Defense

1. e4 e6 {French Defense.}

2. d4 d5

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Modern Defense

1. e4 g6 {Modern Defense.}

2. d4 Bg7

3. Nc3

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Pirc Defense

(Almost all reasonable continuations will suffice.)

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Ponziani Opening

(Almost all reasonable continuations will suffice.)

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Scandinavian Defense

(a) 'Anderssen Defense'

1. e4 d5 {Scandinavian Defense.}

2. exd5 Qxd5 {'Anderssen Defense.'}

3. Nc3 Qa5 {"Prie Defense."}

4. d4 Bf5 {"Besnyo Defense."}

5. Nf3

(b) Marshall Gambit

1. e4 d5 {Scandinavian Defense.}

2. exd5 Nf6 {Marshall Gambit.}

3. d4 {Modern Variation.} Nxd5 {Marshall Variation.}

4. c4

(c) "Vuckovic Attack"

1. e4 d5 {Scandinavian Defense.}

2. exd5 Qxd5 {'Anderssen Defense.'}

3. Nf3 {"Vuckovic Attack."} Nf6

4. d4

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Sicilian Defense

(a) with ...d6

1. e4 c5 {Sicilian Defense.}

2. Nf3 d6

3. d4 cxd4

4. Nxd4 Nf6

5. Nc3

Tip for Black: Don't play ...e5 when your pawn is at d6 unless you know what you're doing. (...e5 makes the d6-pawn backward and therefore likely to be lost, and leaves a hole at d5.)

(b) with ...e6

1. e4 c5 {Sicilian Defense.}

2. Nf3 e6 {Cramling Defense.}

3. d4 cxd4

4. Nxd4

(c) with ...Nc6

1. e4 c5 {Sicilian Defense.}

2. Nf3 Nc6

3. d4 cxd4

4. Nxd4 Nf6

5. Nc3

Tip for White: Don't play Nxc6. (That gives Black a useful tempo upon recapture by a pawn.}

(d) Smith-Morra Gambit

1. e4 c5 {Sicilian Defense.}

2. d4 {Smith-Morra Gambit.} cxd4

3. c3 {"Zelic Attack."} dxc3

4. Nxc3 Nc6

Warning for Black: Don't play ...Nxd4. (That will allow White to centralize his queen.)

(e) Alapin's Variation

1. e4 c5 {Sicilian Defense.}

2. c3 {Alapin's Variation.} d5

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Three Knights Game

(Almost all reasonable continuations will suffice.)

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Vienna Game

1. e4 e5

2. Nc3 {Vienna Game.} Nf6 {Falkbeer Variation.}

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d-pawn openings

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double d-pawn openings

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Blackmar Gambit

1. d4 d5

2. e4 {Blackmar Gambit.} dxe4

3. Nc3 Nf6

4. f3 exf3

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Chigorin Variation

1. d4 d5

2. Nc3 {Chigorin Variation.} Nf6

3. Bg5 {Richter-Veresov Attack.} Nbd7

4. Nf3 h6

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Colle System

(Almost all reasonable continuations will suffice.)

Tip for Black: Leave your c5-pawn there until White captures it; don't play ...cxd4 or ...c4. (Retains tension, avoids useless advance.)

Tip for Black: It doesn't matter whether your KB is placed at d6 or e7. (After dxc5 ...Bxc5 the bishop will end up at c5 anyway.)

Tip for both sides: Castle kingside. (This is standard and probably safest.)

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Mason Variation

1. d4 d5

2. Bf5 {Mason Variation.} Nf6

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Queen's Gambit Accepted

1. d4 d5

2. c4 {Queen's Gambit.} dxc4 {Queen's Gambit Accepted.}

3. Nf3

Warning for Black: Don't try to retain your extra pawn (at c4)! (You will destroy your position trying to do so.)

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Queen's Gambit Declined

(Almost all reasonable continuations will suffice.)

Tip for Black: Don't block your c-pawn with your QN. (That will render your QN largely useless.)

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other d-pawn openings

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Bogo-Indian Defense

(Almost all reasonable continuations will suffice.)

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Budapest Defense

1. d4 Nf6

2. c4 e5 {Budapest Defense Declined.}

3. dxe5 Ng4 {Budapest Defense.}

4. Nf3 {Adler Variation.} c5

5. e3 Nc6

6. Be2 Ngxe5

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Dutch Defense

(Almost all reasonable continuations will suffice.)

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King's Indian Defense

1. d4 Nf6

2. c4 g6 {King's Indian Defense.}

3. Nc3 Bg7

4. e4 d6

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Nimzo-Indian Defense

(Almost all reasonable continuations will suffice.)

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Queen's Indian Defense

(Almost all reasonable continuations will suffice.)

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other openings

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Bird's Opening

(Almost all reasonable continuations will suffice.)

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Dunst Opening

1. Nc3 {Dunst Opening.} d5

2. e4 d4

3. Nce2 e5

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English Opening

(Almost all reasonable continuations will suffice.)

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Grob's Attack

1. g4 {Grob's Attack.} d5

2. Bg2 c6

3. h3 e5

Tip for Black: Play ...Ne7, not ...Nf6. (White will chase off the knight via g5 if the knight develops to f6.}

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Zukertort Opening

(Almost all reasonable continuations will suffice.)

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Isn't it important to know the ideas behind the openings than actually memorizing the lines? what if your opponent takes you out of the book moves early in the opening phase? Then, what would you do ?

Ideas are the important part of the opening, lines come with experience.

I do both: (1) I memorize a few critical starting moves; (2) I learn the ideas behind the openings. It's just that I got tired of making suboptimal moves when I followed only (2). For example, why is 3. Nc3 better than 3. Nf3 after 1. e4 g6 2. d4 Bg7? Why is 2...Nf6 better than 2...Bc5 after 1. e4 e5 2. Bc4? That is way too hard to figure out over-the-board, if it's even possible. Besides, that core memorization allows me to play faster.

If such a thing exists it would have to specify different amounts to learn for different levels of player, for different approaches to the game, for the individual's power of memorisation ...

What can be said fairly certainly is that the higher your standard the more types of position you need to be familiar with, and the more exact lines you have to know.  As a beginner you don't need to know much at all.  It is more important to get good at tactics, and to study lots of master games to get a feeling for the possibilities in chess and what kinds of move are apropriate in various types of position.

As for the opening, you can use resources (books, databases, web sites) aimed at your level, or you can use resources densely packed with variations as well as explanations, that are aimed at all levels of player.  Just focus on the first few moves of the main lines and on the illustrative games.  It is a waste of time memorising long complex variatioons until you are quite strong. It is also near pointless memorising opening lines if:

a) You don't understand why the moves were made, and

b) You don't know (or cannot figure out) what you should be doing at the end of the line

The idea is to gradually increase your opening knowledge as you improve. 

Finally, learning opening variations involves more than simply memorising the sequences of moves.  It is important to challenge the moves that are played.  Ask what does it do?  Does it answer a threat? Does it make a threat? Is it re-organizing the pieces to better co-ordinate? If a piece is developed, whjy to that particular square. If an exchange is made, who does it favour and why? Wha squres are weakened? Which are newly controlled. Is it a mistake giving the other side an opportunity.  WHy not some other move that looks obviously stronger?

I personally think that sqod's advice is rather good if you are prepared to tinker with it and tailor it to your own tastes and temperament. I'm sure he would also agree that an understanding of the principles of those openings is also important. For the club player with the busy life who only plays occasionally in tournaments I'm sure a balance of memorisation to some degree as what I can only describe as a pragmatic triage system and a general understanding of one's chosen openings' strategic ideas is a good time-saving idea. 

I would add the following advice set out here in three parts.

(1) Look at positions from the late opening and early middle game of those openings which interest you at particular snapshot moments of time, particularly the deployment of the minor pieces and the pawn structures. You will similar similar patterns emerging that tend to reoccur. An example might be the broadly similar patterns that emerge for black and white in the Yugoslav Attack of the Dragon and the Saemisch variation of the King's Indian (pawn on f3, bishop on e3 with queen on d2, queenside castling in many lines, etc.). For black the kingside fianchetto and queenside attack are obvious motifs in both. In short look at particular positions as snapshots taking note of how the pawns and pieces are deployed, and think of these deployments as candidate objectives.

(2) Play through some real games (not just theoretical book lines) from top players in which your chosen openings are played which show how positions of these kind are reached. Play them to the end to see what kind of endgames they might produce as well. There is nothing like playing through an entire game to see both the results of opening choices and how strategic ideas work out.

(3) Be sure to look at games in your chosen openings that offer defeats as well as victories for the player with the same pieces that you would approach those openings with. It's very easy in looking for short cuts to go directly to the victories in the hope that those games will offer you the most (possibly even a swindle or two). This, however, is a little short-sighted, I would argue. I have recently been examining, for example, white's play in the Queen's Gambit Declined and found Lasker vs. Capablanca in which black very effectively neutralised the white attack by demobilising the isolated queen's pawn to be extremely useful in thinking about how white should play this opening and the middle game that comes out of it. In short look for examples of your openings which didn't work too well, as these are likely to be as instructive as those where the opening went swimmingly.

Summarising the above, play over real games from top players featuring your openings of choice. Look at late opening, early middle game positions at particular moments in time to think about harmonious piece deployment and pawn structure, consider how those positions are actually reached by playing through those games, and be sure to include games in this process in which your side of the pieces takes a pasting as well as those in which it is victorious. Finally, playing over the games of the good and the great as a way to learn about openings is, I find, actually rather enjoyable, more so that plowing through often dense, and sometimes rather dry, opening books!