Zukertort Opening

The Zukertort Opening is a chess opening named after Johannes Zukertort that begins with the move: 1. Nf3 A flank opening, it is the third most popular of the twenty legal opening moves White has, behind only 1.e4 and 1.d4. Sometimes the name "Réti Opening" is used for the opening move 1.Nf3, although most sources define the Réti more narrowly as the sequence 1.Nf3 d5 2.c4, which happens to be the most common independent variation of the Zukertort. By playing 1.Nf3, White prevents Black from playing 1...e5, and keeps future move options open. It has been described by Edmar Mednis as a "perfect and flexible opening" and by others such as Aron Nimzowitsch as "certainly the most solid move, whereas moves such as 1.e4 and 1.d4 are both 'committal' and 'compromising'." The opening is very often used as a transpositional device into openings that usually start with 1.e4, 1.d4, or 1.c4, where White delays certain committal moves until having more knowledge of Black's plans, usually with the goal of avoiding certain lines possible with a different move order. For example, after 1.Nf3 c5, White can play 2.e4, leading to the mainline Sicilian Defense, or alternatively 2.c4, leading to the Symmetrical Variation of the English Opening. The most common transpositions are to the Queen's Gambit Declined (after e.g. 1.Nf3 d5 2.d4 Nf6 3.c4), the Catalan Opening (after e.g. 1.Nf3 Nf6 2.g3 d5 3.Bg2 e6 4.0-0 Be7 5.c4), and the English. The main independent lines that usually start with 1.Nf3 are the Réti Opening (1.Nf3 d5 2.c4), the King's Indian Attack (where White plays g3, Bg2, e4, d3, and 0-0), and the Nimzowitsch–Larsen Attack (where White plays b3, Bb2, and e3). In these lines, White allows Black to control the center, intending to later undermine that control, in hypermodern style.