I was happy to be practicing mate for supergamer in couple of King's Indian Defences and I thought I'll add here some of the basics.

(Please note that following information is copy/pasted from internet sources and only my part are the game examples.)

From the Indian Games Openings, the King's Indian Defence is one of the most popular Chess Openings.  Being relatively easy to play, is based on solid principles of development and counter attack and at the same time the complexity of the positions which arise, create spectacular combinations and attacks

1. d4 Nf6 
2.  c4 g6 
3.  Nc3 Bg7 
4.  e4 d6
   

The King's Indian is a hypermodern opening, where Black deliberately allows White control of the centre with his pawns, with the view to subsequently challenging it with the moves ...e5 or ...c5.

Until the mid-1930s, it was generally regarded as highly suspect, but the analysis and play of three strong Ukrainian players helped to make the defence much more respected and popular. It is a dynamic opening, exceptionally complex, and a favourite of players such as former world champions Garry Kasparov, Bobby Fischer, and Mikhail Tal, with prominent grandmasters Viktor Korchnoi, Miguel Najdorf, Efim Geller, John Nunn, Svetozar Gligoric, Wolfgang Uhlmann, Ilya Smirin and Teimour Radjabov having also contributed much to the theory and practice of this opening.

Classical Variation

The Classical Variation is 3.Nc3 Bg7 4.e4 d6 5.Nf3 0-0 6.Be2 e5

• The Main Line or Mar del Plata Variation continues 7.0-0 Nc6 8.d5 Ne7. Now White has a wide variety of moves, including 9.b4, 9.Ne1, and 9.Nd2, among others. Typically, White will try to attack on the queenside by preparing the pawn break c4-c5, while Black will attack on the kungside by transferring his knight from f6 to d7 (usually better placed than at e8, as it helps slow White's queenside play with c4-c5), and starting a kingside pawn storm with ...f7-f5-f4 and ...g6-g5. 9.b4, introduced by Korchnoi in the 1970s, used to put top players off playing this line, but it has recently been revived by Radjabov.
• 7....Nbd7 is the Old Main Line, and is playable, though less common nowadays than 7....Nc6.
• 7....exd4 8.Nxd4 is also possible, although White's extra space usually is of a greater value than Black's counterplay against White's centre. Made popular in the mid-1990s by the Russian Grandmaster Igor Glek, new ideas were found for White yet some of the best lines for White were later refuted. White still has an advantage in most lines.
• 7....Na6 has seen some popularity recently. The purpose of this awkward-looking move is to move the knight to c5 after an eventual d5, while guarding c7 if Black should play ....Qe8. Play commonly continues 8.Be3 Ng4 9.Bg5 Qe8! but White has also tried:
  • 8.dxe5 dxe5 9.Qxd8 Rxd8 with even chances;
  • 8.d5 Nc5 9.Qc2 a5 may transpose into the Petrosian System (see below);
  • 8.Bg5 h6 9.Bh4 Qe8 10.Bxf6 Bxf6 11.c5! yet is not totally reliable for Black.
• 7.d5 is the Petrosian System, so named for the 1963-69 world champion, who often essayed the line in the 1960s, with vladimir Kramnik playing this variation extensively in the 1990s. The plans for both sides are roughly the same as in the main variation. After 7...a5 White plays 8.Bg5 to pin the knight, making it harder for Black to achieve the f7-f5 break. In the early days of the system, Black would drive the bishop back with ....h6 and ....g5, though players subsequently switched to ideas involving ....Na6, ....Qe8 and ....Bd7, making White's c4-c5 break more difficult, only then playing for kingside activity. Joe Gallagher has recommended the flexible 7...Na6 which has similar ideas to 7...a5.
• 7.Be3 This line is often known as the Gligoric System, after the world championship candidate who has contributed much to King's Indian theory and practice with both colours. Recently, other strong players such as Korchnoi, Karpov, and Kasparov have played this line. The main idea behind this move is to avoid the theoretical lines that arise after 7.0-0 Nc6. This move allows White to maintain, for the moment, the tension in the centre. If Black plays mechanically with 7....Nc6, 8.d5 Ne7 9.Nd2! is a favourable set-up, so Black most often responds by crossing his opponent's plans with 7...Ng4 8.Bg5 f6 9.Bh4 Nc6, but other moves are also seen, such as:
  • 7...Na6 8.0-0 transposing into the modern.
  • 7...h6!? is a favourite of Jojn Nunn. The main line runs 8.0-0 Ng4 9.Bc1 Nc6 10.d5 Ne7 11.Ne1 f5 12.Bxg4 fxg4. In this subvariation, Black's kingside play is of a different type than normal KID lines, as it lacks the standard kingside pawn roller, so he will now play ...g6-g5 and ....Ng6-f4, often investing material in a piece attack in the f-file against the white king, while White plays for the usual queenside breakthrough with c4-c5.
  • 7...exd4 immediately surrenders the centre, with a view to playing a quick ...c7-c6 and ...d6-d5. For example, 8.Nxd4 Re8 9.f3 c6 10.Qd2 (10.Bf2!?) 10...d5 11.exd5 cxd5 12.0-0 Nc6 13.c5 and 13...e3!?
• In the Exchange Variation (7.dxe5 dxe5 8.Qxd8 Rxd8), White exchanges queens and plays for a small advantage in the relatively quiet positions which will ensue in this queenless middlegame. The line is often played by White players hoping for an early draw, but there is still a lot of play left in the position. White tries to exploit d6 with moves like b4, c5, Nf3-d2-c4-d6, etc., while Black will play to control the hole on d4. In practice, it is easier to exploit d4, and chances are balanced. The central pawn structure is identical to lines of the Ruy Lopez, Chigorin variation, when White also carries out the exchange with dxc5 or dxe5, with reversed colours; in similar fashion, if Black is able to play ....Nd4, he will often have at least an equal game.

The Sämisch Variation is 3.Nc3 Bg7 4.e4 d6 5.f3. It is named after Friedrich Sämisch, who developed the system in the 1920s. This often leads to very sharp play with the players castling on opposite wings and attacking each other's kings, as in the Bagirov-Gufeld game given below, though it may also give rise to heavyweight positional struggles. Black has a variety of pawn breaks, such as ...e5, ...c5 and ...b5 (prepared by ...c6 and/or ...a6). This can transpose to the Modern Benoni after 5....0-0 6.Bg5 c5 7.d5 e6. World champions Mikhail Botvinnik, Mikhail Tal, Tigran Petrosian, Boris Spassky, Aanatoly Karpov and Garry Kasparov have all played this variation. This line defends the e4 pawn to create a secure centre and enables White to begin an attack kingside with Be3, Qd2, Bh6, g2-g4 and h2-h4. It allows placement of a bishop on e3 without allowing ....Ng4; however, its drawback is that it deprives the knight on g1 of its most natural square, thus impeding development of the kingside. Black can strike for the centre as previously mentioned or delay with 6...Nc6, 7...a6 and 8...Rb8 so that Black can play ....b7-b5 to open lines on the queenside.

The classical defense to the Sämisch is 5...0-0 6.Be3 e5, when White has a choice between closing the center with 7.d5, or maintaining the tension with 7.Nge2. Kasparov was a major proponent of this defense.

The Sämisch Gambit arises after 5...0-0 6.Be3 c5. This is a pawn sacrifice, and was once considered dubious. As Black's play has been worked out, this evaluation has changed, and the gambit now enjoys a good reputation. However, a practical drawback is that a well-prepared but unambitious White player can often enter lines leading to a forced draw. The line where White accepts the gambit runs 5...0-0 6.Be3 c5 7.dxc5 dxc5 8.Qxd8 (8.e5 Nfd7 9.f4 f6 10.exf6 is also possible here, though less often seen) Rxd8 9.Bxc5 Nc6. Black's compensation consists of the following factors:

• The King's Indian bishop has an open long diagonal.
• Black has a lead in development, with four pieces in play.
• White's development has been hindered with the pawn placement on f3.
• White has a hole on d4 as well as other good targets for Black's knights.

White's most frequent play is to decline the gambit, and instead play 7.Nge2, and head for Benoni type positions after a d4-d5 advance.

5...0-0 6.Be3 Nc6 7.Nge2 a6 8.Qd2 Rb8 leads to the Panno Variation of the Sämisch. Black prepares to respond appropriately depending on White's choice of plan. If White plays 0-0-0 and goes for a kingside attack, then 7...a6 prepares ....b7-b5 with a counterattack against White's castled position. If instead White plays more cautiously, then Black challenges White's centre with ....e5.

The Averbakh Variation is 3.Nc3 Bg7 4.e4 d6 5.Be2 0-0 6.Bg5 (named for Yuri Averbakh), which prevents the immediate 6...e5. Black usually repels the bishop with ...h6 giving him the option of a later g5, though in practice this is a weakening move. White has various ways to develop, such as Qd2, Nf3, f4 or even h4. However, Black obtains good play against all of these development schemes. The old main line in this begins with 6....c5, though 6....Nbd7 and ....Na6 (Judit Polgar's move) are also seen.

The Four Pawns Attack continues with 3.Nc3 Bg7 4.e4 d6 5.f4 0-0 6.Nf3. This is the most aggressive method for White, and was often seen in the 1920s. With his fifth move, White erects a massive centre at the price of falling behind in development. If Black can open the position, White may well find himself overextended. From this 6...c5 is the main line.

• 6...c5 7.d5 e6 8.Be2 exd5 9.cxd5
  • 9...Bg4 has been a solid line for Black.
  • 9...Re8 can be justified with solid play.
  • 9...b5 is known to lead to sharp, dangerous play.
• 6...Na6 is known as the Modern Variation. This is a move anticipating playing ...Nc5 with counterplay. Has worked with success of neutral moves made from White, such as 7.Bd3. On the other hand, 7.e5 is the most aggressive plan.

The Fianchetto Variation 1.d4 Nf6 2.c4 g6 3.Nf3 Bg7 4.g3 0-0 5.Bg2 d6 6.0-0, is named for White's development of his light squared bishop to g2, and is one of the most popular lines at the grandmaster level, with Korchnoi once its most notable practitioner. This method of development is on completely different lines than other King's Indian variations. Here, Black's normal plan of attack can hardly succeed, as White's kingside is more solidly defended than in most KID variations. The most common variations are:

• 6...Nbd7 with 8...exd4. Black intends to claim the centre with ...e7-e5. 7.Nc3 e5 8.e4 exd4 9.Nxd4 Re8 10.h3 a6! With this move we now can see Black's plans. Preparation has been made for 11...Rb8, with ...c7-c5 and ...b7-b5, and sometimes with ...Ne4 first. This has been known as the Gallagher Variation of the Fianchetto Variation.
  • 8...c6 and 8...a6 are alternatives.
• 6...Nc6 7.Nc3 a6 8.d5 Na5. Although players are taught that knights are not well placed on the rim, here extra pressure is brought to bear against the Achilles Heel of the fianchetto lines-the weakness at c4. Hundreds of master games have continued with 9.Nd2 c5 10.Qc2 Rb8 11.b3 b5 12.Bb2 bxc4 13.bxc4 Bh6 14.f4 (14.e3 Bf5 is a trap which has numbered Mark Taimanov among its victims - White must now lose material, as he has no good interposition) e5!

Updated on July 24 (now incl. training game between KnightLite and me).

Great article and analysis. I fall back on KID when playing Black for first time against a new opponent.