In Guitar Hero: World Tour, I've noticed there are two different kinds of notes that are designed to be used specifically with the slider touch pad on the guitar.
Both types of notes are hollow-ish see-through, but sometimes there is kind of a purple string attaching strings of notes together and sometimes not. What's the string for?
These are called Slider Gems, it means you can play these notes by sliding your finger between them on the slide pad instead of tapping each note.
From the WikiPedia page:
Guitar tracks feature notes connected by a semi-transparent purple line [...] called "Slider Gems"; the player can play these notes by sliding their fingers up and down the touch pad or by tapping the fret buttons without strumming.
I guess I don't know for sure since I have never seen this purple line (though I have definitely seen the "slider gems" and known I didn't have to strum for the note to be accepted should I miss ever since I first observed these "translucent" gems in Guitar Hero 5 I think.) And I can say that I have used both slider and non-slider GH controllers for play to my satisfaction (exactly as the previous answer describes), yet I have still not seen this purple line - but I am playing on the Wii, which I understand is relatively rare, both in terms of overall hardware and on SE (though I hope I'm wrong about that last part and others can relate to me on the Wii system!)
