Ghost notes add percussion, funk, and flair to your bass playing. Whilst it's true that the technique is primarily heard in funk music, you can actually use them in a whole range of styles.
Watch this video lesson to find out how to play them as well as incorporate them into your playing and practice.
I go into ghost notes a lot in my book 100 Funk Bass Grooves.
If you want to delve further into ghost notes and articulations (hammer-ons, pull-offs, bends, slides, vibrato) then take a look at these video lessons:
Learn This Cool Bass Lick! (Hammer-Ons, Pull-Offs, Ghost Notes, Raking, Slides)\
Bass Guitar: Hammer Ons, Pull Offs, Ghost Notes, String Bends, Slides and Vibrato
5 Absolutely CRUCIAL Bass Techniques To Know!