The total set of possible colors captured by your camera, and their relationships to each other, are known as a color space. Your DSLR may be able to use two or more color spaces.

sRGB is the standard color space for most digital cameras, computer monitors, and desktop printers. It is a convenient option for viewing editing images on a desktop computer.

Adobe RGB
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)_