Yes this is a ghost note. In most cases it may or may not be played, and if it is played it is a very subtle note that can usually barely be heard, hence the name ghost note. Or it may have been added in the studio after the fact. There's so many things done in the studio it makes it hard for the average player to totally replacate a song not for note. The best thing to do is play the note and then not play it and see if it really makes a difference in the context of the song. Also I think 95 percent of tabs even in publications are just attempts @ replacating a song and unless the artist was solicited for a note for note replacation of the song a TAB will never be 100% correct. That's all the knowledge I have on this subject. Also try using the search option. I believe remembering this subject being raised for discussion a couple times in the past. Hope that helps you out! ;)