In string theory, physicists tell us the subatomic particles that make up our universe are created within 10 spatial dimensions (plus an eleventh dimension of "time") by the vibrations of exquisitely small "superstrings."
The average person has barely gotten used to the idea of four dimensions. So, how can we possibly imagine the 10th?
This amazing animation is the best I have yet to see to help explain the differences between the 10 dimensions, based on string theory. Check out the awesome links below for more on string theory and exploring the 10 dimensions.