Slav defence

The Slav defence is an important reply to 1d4. It is popular with top players. The Slav usually begins:
Other fourth moves for White are 4.e3, 4.cxd5 and 4.Qb3.
The Slav proper.
Now 4...dxc4 is the Slav:
Mainline.
This line was explored in two world championship matches between Alekhine and Euwe in 1935 and 1937.
The Semi-Slav.
The Russian variation.
Sometimes called the Botvinnik variation.