One of several possible options.

As black, this is also what I would've played.

Another of putting is, "Stick with what you know".

This is playable, but enters obscure territory. Good moves are 3.c4, 3.Bf4, 3.Bg5, 3.e3, 3.g3, even 3.Nbd2 isn't bad. What this knight move does is block the c-pawn's advance. That isn't bad, exactly, but it requires White to play the sort of game in which the c-pawn's advance is not required - or at least, not soon.

ION is spot on.

You mean that he knew what to do.

There is no pin. Imagine the White e-pawn on e3, then the knight would be pinned by the g4-bishop against the Queen. ++++++++ The pawn attacks the bishop, as intended. But as the pawn is attacking but one target, it is not a fork. Prod, yes; pointy stick, OK; boot, fine. This pawn hit is sometimes called 'biffing the bishop!'

It would, however, be a fork if black's Queen was on d6, and white were able to play e5 as then, the Knight and Queen would be attacked by a pawn.

When Black played the bishop to g4, he would have had - or ought to have had - a clear idea what his response would be to having his bishop biffed. He chose to exchange. Retreat, in the direction from which it came, or to h5, were also both reasonable options.

Agreed, exchanging was not best for black. Don't forget that it's Knight for Bishop, and a Bishop is generally worth more.

Pawn capture 'towards the centre'. That is a useful guideline, and it's fine here. It adds strength to White's centre, makes the e2-e4 pawn break likely, gives White a nice half-open g-file for a rook. The downsides, the doubled pawn and the isolated h-pawn are relatively trivial by comparison. ++++++++++++ Had White taken with the e-pawn, it would have sped up her development at the cost of a slight weakening of the centre. I think she chose marginally the better option, but I would not have criticized the alternate recapture IN THIS POSITION.

Neither would I.

Added protection to d5, and frees the bishop. By exchanging, Black has avoided any problems with his light-square bishop being on the same colour squares as those centre pawns. I forget to mention, though, that White's bishop pair might well become a factor in this game.

Which is why it's generally not a good idea to exchange just because it's possible, especially Knight for your Bishop.

Understandable, and looks reasonable. But I would not have played that. Good alternatives were 6.e3 or 6.e4 or 6.Bf4 or 6.Bg5, the bishop moves to get the bishop into action before advancing the e-pawn. The e-pawn having advanced, the light-square bishop could have played to d3, eyeing the K-side, the Q move to d2, and the White castle Q-side (0-0-0), Then she could start planning an attack on the K-side.

The only reason why I would've played this would be to castle on the next move. But, I agree with ION. As it would boil down to castling into an attack.

Now this really is a pin - the bishop pins the knight against the King. It is not a very onerous pin, except that Black might be interested in exchanging on c3, leaving White with two pair of doubled pawns, and isolated pawns on both extreme flanks. Should White avoid that possibility or not? That is a judgement call. See my further comments infra.

Erika asked me to show her examples of a pin. This is certainly one of them, and it's direct since the Nc3 can't move here.

OK: forces Black to commit to a decision at once. If White wanted to avert a second set of doubled pawns, the she could have played 7.Qd3 or 7.Bd2. But for all the pawn weakeness that accrue, there is a persuasive upside to White's decision. I might have played 7.a3 myself in this position.

I would've played 7.Bd2 but feel that it's too passive because of what ION just mentioned. So, I think that white made the right decision here.

Material is level, but the position is dynamically asymmetrical - fascinating position. Look at that mass of White pawns in the centre files! That is a formidable weapon with which to establish a preponderance on that part of the board. One the Black centre is beaten down - if it can be beaten down - then White's pair of bishops might well come into their own.

No worries. I'd probably play 9.e4, here, with the idea 9...dxe4 10.fxe4 ... (undoubles one pair of pawns) 10...0-0 11.Be3 or 11.f4 with a really big centre (the following diagram is after 11.f4): If Black doesn't take on e4, then maybe 9.e4 0-0 (say) 10.e5 ... In both lines, White would probably defer castling indefinitely, maybe for good, parking the King on d2. Both these positions look quite playable for White.

For me, no worries is also about not being nervous. If you have questions, it's always a good idea to take your time and try to figure out where you want to go or what you want to do, Erika. As they say, slow and steady wins the race. That's where I think in terms of Turtose, as opposed to, The Hair.

Understandable, and reasonable. Not what I would have played, but it looks probably OK.

That is a very good move by Black Although this opens the centre up a little before his King is castled, he isn't risking much.

True, it's become a very interesting position.

I'm not sure myself what would be best to play. Moves like 10.Bg5, 10.e4 and 10.e3 all come into consideration... as does this capture, of course.

Materialwise yes, but I think that you've got an edge because of what archduke_piccolo noted earlier.