Tarrasch Defense

Named after Siegbert Tarrasch. Black accepts an isolated d-pawn in return for free piece play; Garry Kasparov used it in his first match against Anatoly Karpov.

It is reached after 6 moves: 1. d4 d5 2. c4 e6 3. Nc3 c5.

White is to move and has 33 legal moves. Over the next four moves — two for each side — the game can branch into 1,167,337 different games. Those games reach 369,434 different positions: most positions can be reached in more than one way, 3.2 on average.

The Lichess opening list names 34 further lines after this position, such as Queen's Gambit Declined, Tarrasch Defense (4. cxd5 exd5) and Symmetrical Variation (4. e3 Nf6 5. Nf3 Nc6).

The same moves can be played in 18 different legal orders that all reach this position. For example 1. c4 d5 2. d4 e6 3. Nc3 c5, which starts as the English Opening.