What is Negative Space?

Legal Definition
Negative space, in art, is the space around and between the subject(s) of an image. Negative space may be most evident when the space around a subject, not the subject itself, forms an interesting or artistically relevant shape, and such space occasionally is used to artistic effect as the "real" subject of an image.
-- Wikipedia
Legal Definition
Unconfirmed standby seat booking as a travel industry term. Contrast to positive space.