The two basic color spaces, or Modes, that you’ll most often encounter with your digital images are RGB and CMYK. Each has a specific use, outlined below.
RGB (Red-Green-Blue) is the color of the light emitted from your computer monitor, and from TV’s. Use RGB if you are taking photos specifically to be viewed onscreen, such as the internet, or for a CD or emails. RGB usually also works well for printing from your home or officeprinter.
CMYK (Cyan, Magenta, Yellow, Black) is the color of inks used in the offset printing process. Use CMYK if you are sending your photo to be printed, such as preparing a postcard to be professionally printed for a gallery invite.