Vermeer, The Girl with the Pearl EarringJohannes Vermeer

The Girl with the Pearl Earring  (1665)

Who is this girl?

Why is she looking over her shoulder, as though hoping to see who is standing behind her.

What has made her turn her head?

She gazes at us, wide-eyed, making an uninhibited, expectant impression that cannot help exciting our interest, even though we have no idea who she is.  (Wikipedia, Mauritshuis Netherlands)