What Does the 3 in the Integral Notation \int{d^3 r} Represent?

[DanielFaraday]

I saw this notation in a textbook but I'm a bit confused by it. What exactly does the 3 mean? Is it shorthand for a triple integral in spherical coordinates?

\int{d^3 r}

Thanks in advance.

 

[mathman]

It means a triple integral, not necessarily in any particular coordinate system.