Although it was analyzed as early as 1590, it was not until the 1920s that it started to be explored extensively, although Steinitz essayed it in the first official World Chess Championship of 1886.
Many masters of Slavic descent helped develop the theory of this opening, including Alapin, Alekhine, Bogoljubov, and Vidmar.
Played by 11 of the first 13 world champions, this defense was particularly favored by Euwe, Botvinnik, and Smyslov.
More recently the Slav has been adopted by Anand, Ivanchuk, Lautier, Short, and other top grandmasters, including use in six of the eight games that Vladimir Kramnik played as Black in the 2006 World Championship (in the other two, he played the related Semi-Slav Defense).
Black's queen bishop is unblocked; the pawn structure remains balanced.
White can also try the following alternatives: Black often plays 3...Nf6 but 3...Bf5 is considered to be an easier equalizer.
The Exchange Variation was once described as "the system that takes the fun out of playing the Slav" for Black.
To avoid the possibility of the Exchange Slav Black often chooses the move order 2...e6 followed by 3...c6 to enter the Semi-Slav, this is known as the Triangle System.
Black can try the Winawer Countergambit, 3...e5, which was introduced in Marshall–Winawer, Monte Carlo 1901 but this is thought to be slightly better for White.
3...e6 may lead to various possibilities, such as the Noteboom Variation, Semi-Slav Defense or Stonewall Dutch.
The most common continuation is 4...Bf5 5.Nc3 e6 6.Nh4, when White wins the bishop pair but Black gets a solid position and often gets counterplay with ...e5.
Evaluation of this line changes as improvements are found, but as of 2005 it is generally thought to favor Black.
With the Smyslov Variation, 5...Na6, Black allows the e-pawn to come to e4 but can gain counterplay by ...Bg4 and perhaps bringing the knight to b4 e.g. 6.e4 Bg4 7.Bxc4 e6 8.0-0 Nb4.
A more energetic line begins 6.Ne5 (Krause Attack) where White intends f2–f3 and e2–e4 or Nxc4, perhaps followed by a fianchetto of the king bishop with g2–g3 and Bg2.
Black can try either 6...Nbd7 7.Nxc4 Qc7 8.g3 e5 (known as the Carlsbad Variation) or 7...Nb6 or 6...e6 7.f3 Bb4, when 8.e4 Bxe4 9.fxe4 Nxe4 is a complex piece sacrifice with the semi-forced continuation 10.Bd2 Qxd4 11.Nxe4 Qxe4+ 12.Qe2 Bxd2+ 13.Kxd2 Qd5+ 14.Kc2 Na6.