We have talked about photoshop, and color theory. Color theory is based on 16 based number system. So in the number system we are using, you have ten, then hundred, then thousand, then ten thousan, and etc. In 16 based number system, you have 1, then 16, then 256. Numbers after 9 are represented by letters, from A to F. So the biggest number you cam get is FF which is 255. That's why there are 255 different shades of color. There are three primary colors: Reed, Green, Blue. All together they make white. Each shade of color has its own code, which is made using 16 based number system. So if you need one color in two different files, you can find it by its code.