King's Indian Attack: Symmetrical Defense is a chess opening with the ECO code A05, part of the King's Indian Attack family. It goes 1. Nf3 Nf6 2. g3 g6. White opens with 1. Nf3 (the Zukertort/Réti knight move) and Black answers 1... Nf6. After 4 moves it is White to move. The lesson on the board explains every move of the line and lets you play it yourself; it is free.
The moves
1. Nf3 – White plays the knight to f3
1... Nf6 – Black plays the knight to f6
2. g3 – White plays the pawn to g3
2... g6 – Black plays the pawn to g6
About the King's Indian Attack
White sets up Nf3, g3, Bg2, O-O, d3 and later e4: a King's Indian with colours reversed. It is an easy system against almost anything.
White plays Nbd2, e4 and often e5 to gain kingside space.
With a pawn on e5, White attacks with Nf1, h4 and Ng5 or Nh2-g4.
Black usually expands on the queenside with ...c5, ...b5 and ...b4.