Annotated chess game

Strong move.

blunder a3 uh oh loss of piece

This is a blunder, as counto says 12.a3 wins a piece because your knight can't go anywhere. 11...Nb8 was forced and that's why 11.b5 was a strong move.

12. a3 and your knight is trapped. White now is ignoring basic opening principles - don't start an attack until all your pieces are out. That lone knight is going nowhere.

No need; as I said, it was going nowhere. You need to give your knight an escape route somehow. c6 seems the only way.

This is a bad move because after 14.Ng3 there's no way to save the knight if he plays 15.a3.

Bad move by white; again, a3 just won a piece. ***Edit*** - @jkarp: Yes.

@jkarp: strange comment, cdeburca is right. How would you save the knight after 15.a3?

I would've played 15...Nxc6 because your knight is still misplaced, but this is ok too.

b1 to b4

How could she possibly take your rook?! ***Edit*** - it seems the two of ye have trouble with the names of pieces!   I assume the annotator is referring to the rook taking the knight.

No you can't (well, I'm assuming you meant to say "I can take that pawn"!). It's protected. You need to count the number of pieces defending and attacking a piece/pawn before exchanging. If your opponent has more defending than you have attacking, don't go in for the exchange; you're going to lose.

It was never a free pawn - it was an exchange of pawns (followed by which you gave up a free bishop)

fork! ur gettin beat

Completely missed the rook being attacked! Thanks counto.

! A good move, as Qa5+ later on will recoup the piece, so you wind up a pawn up.

19.Bxf8?? is bad because of 19...Nxc3 20.Qc1 Nxb1 21.Qxb1 Kxf8where Black has won a piece.

19...Qa5+ was better because you win either the knight on a2 or the bishop on c5.

In this case, 20.Be3 was best because then 20...Qa5 is not harmful anymore due to 21.Qd2 (the bishop has moved away from c5 so it can't be taken, and the knight on a2 is protected by the queen then).

White is two pieces up; there is no way black has a winning position.