what happend in this move?

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TheFox1

hi In this thread I want to ask if anyone in this website get the same error before first of all I think that chess.com is the best chess website to play but today I get a error that shocked me this is 

is the first time that I get this error in this website look 15. f5 move and 16. gxf6 , it happened to someone else? 

trysts

En passantWink

blueemu

Not an error. It's a chess move.

http://en.wikipedia.org/wiki/En_passant