What is voice?

Editors always say they want a protagonist with a great voice - gumption - verve - individuality. I've begun to collect images that scream 'voice' to me. Here's a good example from Daily Dawdle:

     I bet she's got a pretty powerful voice to write about, eh? Is she a tomboy? Or maybe she's just angry - why? Even better that she's a girl getting the upper hand. (In pink, no less.) The people in her world would be foolish to underestimate her. And who doesn't feel like this sometimes? See how the story practically starts to unfold itself?
     That's voice.