This color space has more possible colors than sRGB (i.e. it has a wider gamut). It is suited to more extensive editing and commercial press publication. However, you will need to use appropriate color management and profiles in order to get good results, so use the Adobe RGB space only after you're comfortable with the required workflow.
Adapted from 40 Digital SLR techniques by Darrell Tan (Youngjin, 2006; $17)_