Knight sacrifice performed by Deep Blue against Garry Kasparov Below is the 1997 game of Deep Blue VS Garry Kasparov:

r1bqkb1r/pp1n1pp1/2p1pn1p/6N1/3P4/3B1N2/PPP2PPP/R1BQK2R w - - 0 1


The last move 7...h6? was played by Kasparov (black), after which Deep Blue played the knight sacrifice 8.Nxe6.

Wikipedia says:


  The computer is aided by having this knight sacrifice programmed into its opening book. This move had been played in a number of previous high-level games, with white achieving a huge plus score. As an indication of how far computer chess has progressed in the 20 years after this match, modern programs deprived of their opening books are able to correctly evaluate Nxe6 as strongest; but at the time this was played it was considered probable based on other programs' performance that it was only the opening book that was responsible for this choice. The compensation white gets for the material is not obvious enough for the computer to see by itself.


How would white compensate for their sacrificed knight?
History of this line is interesting. People used to think it's good for white, maybe majority still do as well as openings books do. But in correspondence database I use there are four games with Nxe6 fxe6 and black scored two wins and two draws out of four games. The wins are from 2012 and 2013. I know a lot of white players avoiding the sacrifice these days as it is easy to lose even against much weaker opposition while it doesn't even have the objective quality. Black play is easier and more obvious. I don't like White's position, I like Black here. It is too closed without direct threats for such a material investment. I know mainly the defensive plans for black here as it is in my repertoire, ok white try to play on e-file, disrupt you with Ne5 and f7 fork threat, may want to play c5 with B/Qa5+ sometimes and even b2-b4-b5 as black is undeveloped for quite some time. It is positional sacrifice and very interesting one.