Color balance adjustments are most often thought of as ways to eliminate an undesirable color cast within an image. To make areas that should be neutral in the image truly neutral.
In graphics and image-editing programs, color adjustment(s) can be used to change the overall tone of your image and also to remove unwanted colors from your image. Color adjustment changes usually affect an entire image, even if you have selected only a small portion of the image to be adjusted. If you are working with images that are 24-bit or higher you may be able to make these changes to a specific part of the image.
Color adjustments can also take other colors from the image into consideration when running the algorithm.
One element of color adjustment that is available in many graphics programs is color balance. This function allows you to control the amount of red, green and blue in an image. Other standard color adjustments found in many graphics program allow you to adjust the brightness, contrast and gamma in the image. These options are used to correct the brightness and contrast of an image. Adjusting the brightness and contrast highlights mid-tones and shadows to bring out detail in either light or dark areas. Gamma adjusts the brightness and contrast in unison.
There is two ways to apply color adjustment :
1) Image –>Adjustments
2) Using Layer palate –> Adjustment Layer