Why does Black play 6...c6 in this position?

SupremeRule wrote:

Why does Black play 6...c6 in this position? What type of strategic game ensues this decision? What are some common motifs and ideas in this variation?

6 ..c6 is far from the only move. Is this your homework? The questions sound like homework-type questions.

Why don't you try to answer the questions first? You won't gain anything unless you do.

Hi my name is John Johnsen. FIrst of all in this line black always wants to play c6 at some point because his queen wants to go to either a5 or c7, usually c7 where it is well played and allows a rook to go to d8. then black has a choice between 2 followup ways of playing. a) he goes a6 after c6 and plays with b5 or he puts his queen on c7 and knight on d7 and pushes e5.

I've seen plans for Black where after c6-Qe8-e5 are played, but I don't think it's the best way to play. 

I also think Black can play d5 after many of white's replies, which is a bit curious, but sound nontheless. For instance, 7. O-O d5 8. cxd5 cxd5 9. Ne5 Nc6 (and white's probably insignificantly better).

I think more often you'll see 6.Nbd7 with the plan of either c5 or e5, rather than c6. In these c6 set-ups black tends to be a bit slow on whichever pawn break they choose, which in many positions allows white to maintain a slight edge (and in many cases a space advantage). 

Yeah, I know its not the only move. And yes, it is preperation for a tournament. 6...Nc6 and 6...Nbd7 are more popular, but my question is not restrained to this position. I never understood why c6 is played in other KID variations.

My explanation:

I think c6 is played in order to give the black queen some squares to develop to like a5, b6, and c7. Not only that, in many cases White pushes d5 which gives Black the option to take and open the c file for his rooks(remember that Botvinnik-Tal 1960 game when Tal sacrificed a knight on the kingside then won?)

Is this a good explanation?

Wow, the Feynman Technique really works!

Another type of action that ..c6 makes possible is ..Qa5-h5 combined with either ..Bg4 pinning or ..Bh3 attempting to exchange the light squared bishops.  This only makes sense against the fianchetto variation, for obvious reasons.

OP did you read my post? I told you the exact reasons and i know them so well because i play like this with both white and black at times...

I play this with both white and black (Grunfeld) as well, albeit at a much humbler level. In my more limited experience the black pawn on c6 can also makes white's potentially rather dangerous fianchetto'd bishop quite ineffective in those continuations that lead to more closed positions. 

An idea in this position could be the battle of light square versus dark square control. In the Bg2 KID line, white looks to be better on the light squares with usually c4, e4, Nc3 and Bg2. If d5 can be taken with no resistance, it binds black and usually then a c6 or e6 to break the bind is weakening. So black can hinder d5 with preemptive ...c6.

Then if d5, cxd5 closes the center blunting Bg2 and offers compensation for the bind on d5. I think the Botvinnik-Tal 1960 game might be an example.

Black can also follow up ...c6 with ...e5 questioning whites d4. If white doesn't d5, black, can take and try for equivalent dark square control. Probably much sharper play and can mean giving up d5 square control which might not turn out great as in Karpov-Kamsky 1995.

I agree with this and also I'd point out the the c6 pawn restricts white's c3 knight. With one pawn move black weakens two of white's pieces and increases the activity of his own queen.

Thanks!, I didn't see your comment.

That is very interesting. So 7.O-O Qa5 8.e4 Qh5 9.Ng5! preventing the trade of light squared bishops