There are three common ways to specify color for use in traditional offset printing and for on screen viewing (like for web sites) and inkjet printing: RGB, CMYK and Pantone. if you are working on your computer on things intended for onscreen viewing or inkjet printing then you are probably working using the RGB color specification  if you are doing the regular offset printing (without special spot colors) then CMYK is probably what you’ll be dealing with. Pantone is the gold standard for getting precise color with offset printing (and gives you some colors you couldn’t get with just CMYK alone) but even the Pantone system isn’t perfect and using Pantone could potentially add to your job cost if you are already doing regular color photos.