Negative space is the space around the subject of an image. For example, if you have a picture of a ball, the negative space in that picture is everything around the ball.
The clever artist can use negative space to communicate a supporting or secondary idea. With the ball example, that picture could have the ball smack in the middle of an otherwise blank image to convey the idea of a ball sport in Japan.
Actually, it’s useless to explain it in words. You get a better idea if you see for yourself.
More at the source:
- Negative Space – really cool pictures on artist’s site
- 30 Clever Examples of Negative Space Logos
- Negative Space – big words and long sentences on Wiki