Inaccuracies

A small question: how do chess masters recognize chess inaccuracies and what categorizes an inaccuracy? I recently watched a video commentated by Magnus Carlsen and he mentioned a move of his opponent's being "slightly inaccurate." Can anyone clear my confusion?

- Masquerade

If you can give a reason why a move is not inaccurate, I'll tell you why it's inaccurate.

In this position, Carlsen considered taking on c7 with the pawn an inaccuracy: lichess.org/editor/r4rk1/2q1bppp/p1Pp1n2/np2p1B1/4P1b1/2P2N2/PPB2PPP/RN1QR1K1_w_KQkq_-

This middle game position resulted from the Spanish game.

Explain please (in the position you give there is no pawn which can take on c7)

Ah i see, you mean taking on c6 with d5 pawn. Here d5xc6 is an inaccuracy because it allows Nc4, attacking b2, and white has no good looking moves to protect it. And if he plays b3, then N can go to b6 and c3 is a weakness which black will attack on the half open c-file.

Instead Nbd2 is better, which prevents that idea. But white is slightly worse here too as he played d4-d5 without being able to protect his d5 pawn with c3-c4 on ..c7-c6.

A (very) general rule of thumb in the Ruy Lopez is: If white wants to play d5 he prepares it with b2-b3 to have c3-c4 on ..c7-c6, so that his pawn structure which gives him a space advantage stays intact.

@awesomer Thanks for your very concise explanation. It is obvious that you have been around the chess board for a while. Do you have any tips on spotting inaccuracies, to better improve my game?

#7 Yes: Replay Master games. Eg. start here:

http://www.chessgames.com/perl/chesscollection?cid=1008909

if you dont like the games, check out this website:

http://www.chesscorner.com/games/games.htm

Replay these games on a real chess board (btw, joining a chessclub is always helpful). Play the openings from the games you replayed. With both colors. If your opps play an opening you do not know, check out the opening eg. here:

http://www.dwheeler.com/chess-openings/

Play the openings which work best for you. Use the analysis feature here but dont use any chess engines.

Do 3 to 5 tactics here or on chess tempo every day.

When you reached 1800 message me, then i give you a link to a simple endgame book.

Then you should be on a level where you dont need any assistance anymore.

That would be my suggestion.

@awesomer Will do.

Addon to #8:

Here is part 2 (semi-closed games) and 3 (closed games) of the first link:

http://www.chessgames.com/perl/chesscollection?cid=1008935
http://www.chessgames.com/perl/chesscollection?cid=1008936