The RGB model was created to sense, represent, and display images for electronic systems. This is done by combining the colors red, green, and blue together at various proportions to produce a unique color. These three values are scaled between 0-255 to display a color like this RGB (79-134-247).
Then to simplify the RGB color code for HTML and CSS use the Hex (Hexadecimal) color code was created. The code itself is a hex triplet where the 0-255 RBG scale translates to a 00-FF value. Compacting a color like RGB (79-134-247) into a 6-digit code such as #4F86F7. The Prime Colors (Red, Green, Blue, Yellow, Cyan, Magenta, White, and Black) represent the eight possible combinations utilizing the colors RGB (Red, Green, and Blue) to their minimum (00) and maximum (255) outputs.