English Opening

The English Opening is a chess opening that begins with the move:
A flank opening, it is the fourth most popular and, according to various databases, anywhere from one of the two most successful to the fourth most successful of White's twenty possible first moves. White begins the fight for the by staking a claim to the d5-square from the wing, in hypermodern style. Although many lines of the English have a distinct character, the opening is often used as a transpositional device in much the same way as 1.Nf3 – to avoid such highly regarded responses to 1.d4 as the Nimzo-Indian and Grünfeld Defences — and is considered reliable and flexible.
The English derives its name from the English (unofficial) world champion Howard Staunton, who played it during his 1843 match with Saint-Amant and at London 1851, the first international tournament. It did not inspire Staunton's contemporaries and caught on only in the twentieth century. It is now recognised as a opening that may be used to reach both classical and hypermodern positions. Mikhail Botvinnik, Tigran Petrosian, Anatoly Karpov, Garry Kasparov, and Magnus Carlsen employed it during their world championship matches. Bobby Fischer created a stir when he switched to it from his customary 1.e4 late in his career, employing it against Lev Polugaevsky and Oscar Panno at the Palma de Mallorca Interzonal in 1970, and in his world championship match against Boris Spassky.
Taxonomy.
Opening theoreticians who write on the English Opening divide it into three broad categories, generally determined by Black's choice of defensive setup.
Symmetrical Defence: 1...c5.
The Symmetrical Defence (classified A30–39 in "ECO") is 1...c5, and is so named because both of the c-pawns are advanced two squares, maintaining symmetry. Note that Black can reach the Symmetrical Defence through many move orders by deferring ...c5, and often does. For example, 1.c4 Nf6 2.Nc3 (or 2.Nf3) c5.
Either player may make an early break in the centre with the d-pawn.
Similar to the Open Sicilian, an early d2–d4 for White can arise on the third move in the Symmetrical Defence with 2.Nf3, where Black has chosen one of 2...Nc6, 2...e6, 2...d6, or 2...g6. 
After 3.d4, the game usually continues with 3...cxd4 4.Nxd4. The games can give a large variety of positional and tactical ideas, and can transpose into variants of the Open Sicilian involving the Maróczy Bind, such as the Accelerated Dragon, Taimanov, Kan, or Kalashnikov Variations, if White plays e4 in a later move. If Black manages to play d5 before White plays e4, then the game could transpose into variants of the Queen's Gambit Declined.
When Black plays 2...Nf6, these lines are often called the Anti-Benoni, since these positions are often reached after the transposition 1.d4 Nf6 2.c4 c5 3.Nf3, where White avoided the Benoni Defense that would arise after 3.d5. After 3...cxd4 4.Nxd4, Black could follow up with 4...e5 forcing White's knight to go to the queenside and avoiding the transpositions to the Sicilian or the QGD; however, White could avoid the line by first playing 3.Nc3 and then play 4.d4, if Black doesn't play 3...d5 (see below). Same as above, the position could transpose into a Queen's Gambit Declined or an Open Sicilian involving the Maróczy Bind. 
There are several types of positions that can arise from the Symmetrical Defence. Among the ideas are:
Reversed Sicilian: 1...e5.
The Reversed Sicilian (classified A20–29 in ) is another broad category of defence, introduced by the response 1...e5. Note again, that Black can delay playing ...e5, for example 1.c4 Nf6 2.Nc3 Nc6 3.Nf3 e5 whereupon even though ...e5 has been delayed, once it is played the defence is classified as a Reversed Sicilian.
After 1...e5, White has Black's position in the Sicilian but with an extra tempo. This is often called the Reversed Sicilian, though others call it the King's English. Bruce Leverett, writing the English chapter in "MCO-14", stated, "It is natural to treat the English as a Sicilian reversed, but the results are often surprising—main lines in the Sicilian Defence correspond to obscure side variations in the English, and vice versa."
Other lines.
The third broad category consists of the non-...e5 and non-...c5 responses, classified A10–19 in "ECO". Most often these defences consist of ...Nf6, ...e6, and ...d5 or ...Bb4 systemic responses by Black, or a Slav-like system consisting of ...c6 and ...d5, a direct King's Indian Defence setup with ...Nf6, ...g6, ...Bg7, ...0-0, after which ...c5 and ...e5 are eschewed, or 1...f5, which usually transposes to a Dutch Defence once White plays d4. All irregular responses such as 1...b6 and 1...g5 are also lumped into this third broad category.
Responses include
Transposition potential.
If White plays an early d4, the game will usually transpose into either the Queen's Gambit or an Indian Defence.
For example, after 1.c4 Nf6 2.Nc3 g6 3.d4 d5 the game has transposed into the Grünfeld Defence, usually reached by the move order 1.d4 Nf6 2.c4 g6 3.Nc3 d5.
White can, however, also play 1.c4 Nf6 2.Nc3 g6 3.e4, making it impossible for Black to reach a Grünfeld, instead more or less forcing him into lines of the King's Indian Defence with 3...d6. Black also cannot force a Grünfeld with 1.c4 Nf6 2.Nc3 d5, since White can deviate with 3.cxd5 Nxd5 4.g3, a line played several times by Mikhail Botvinnik in 1958, in his final match for the world championship with Vasily Smyslov.
Instead of playing an early d4, White can also play Nf3 and fianchetto the (g3 and Bg2), transposing into a Réti Opening.
Also, after 1.c4 c6, White can transpose into the Polish Opening, Outflank Variation, by playing 2.b4, which can be used as a surprise weapon if Black does not know very much about the Polish Opening.
The many different transpositional possibilities available to White make the English a slippery opening for Black to defend against, and make it necessary for him to consider carefully what move order to employ. For instance, if Black would like to play a Queen's Gambit Declined (QGD), the most accurate move order to do so is 1...e6 2.d4 d5. (Of course, White can again play the Réti instead with 2.Nf3 d5 3.b3.) If Black plays instead 1...Nf6 2.Nc3 e6, White can avoid the QGD by playing 3.e4, the Flohr–Mikenas Attack.
"ECO".
The "Encyclopaedia of Chess Openings" has classified the English Opening under the codes A10 through A39:
Depiction in cinema.
The English Opening is used by Professor Moriarty in the film "" as he and Holmes discuss their competing plans over a game of chess. Both Holmes and Moriarty eventually play the final moves blindfolded by citing out the last moves in descriptive notation (rather than algebraic, as the former was contemporary in the late 19th century), ending in Holmes checkmating Moriarty, just as Watson foils Moriarty's plans.
1.c4 is also used in "Pawn Sacrifice" by Bobby Fischer in the climactic game six of the 1972 World Chess Championship versus Boris Spassky.