Hue/Saturation lets you adjust the hue, saturation, and lightness of a specific range of colors in an image or simultaneously adjust all the colors in an image. This adjustment is especially good for fine-tuning colors in a CMYK image so that they are in the gamut of an output device.
You can save Hue/Saturation settings in the Adjustments panel (CS5) or the Properties panel (CS6), and then load them for reuse in other images. For more information, see Save adjustment settings and Reapply adjustment settings.
For more information on image adjustments, see Adjusting image color and tone in CS6.