Spanish Defense ..g6,Bg7

a popular plan for Black is to play d6,g6,Bg7 in the Spanish Defense. We will see how White should respond 

 1. e4 e5 2. Nf3 Nc6 3. Bb5 a6 4. Ba4 Nf6 5. d3 d6 6. c3 g6

There is no obvious refutation, White should continue development.

7. O-O Bg7 8. Re1 O-O 9. Nbd2 

This is a key position for this variation. Black has a lot of options here to continue. The best way is to illustrate all the possible 9th moves with arrows. white usually plays Nf1-g3

in the next diagram. This is a lot of ground to cover.

Variation A: Black plays 9..Nh5 right away.

9..Nh5 10Nf1 f5 

11. exf5  11... Bxf5 12. Ng3  12... Nxg3 13. hxg3 b5  14. Bb3+  d5 

Here we are in the game Miton-Shirov 2009, but I recommend 15d4!with 15..e4 16 Ng5 followed by f2-f3 which is very strong for White.

Variation B: Black plays ..h6 to prepare a future f7-f5

 9..h6 10. Nf1 10... b5 11. Bc2 

11... d5 12. Bd2

12..Be6 13. a4 13... Qd6 14. b4 Nd7 15. Bb3 

15..dxe4  16. dxe4 Nb6  17. a5 Nc4 18. Ne3

Nepomiachi-Akopian 2010, White is slightly better 

Variation C: 9..Nd7 10Nf1 Nc5 11Bc2 (11. Bxc6 bxc6 12. d4 Anand-Caruana 2018)Ne6

12. Ng3 Bd7 13. h3 Kh8 (13..f5? 14ef5 gf5 15d4! with threat d4-d5)

14 Ne2!? (14Be3) Ne7 15. d4 with ideas Be3 and a2-a4

Areshchenko,A (2673)-Matta,V (2246) 2009