The RGB (Red Green Blue) color system is an additive color model. The brightness of Red, Green, and Blue is combined together to reproduce a broad array of colors.
This system is used to represent the colors on a computer display. The red, green and blue use 8 bits each, which have integer values from 0 to 255 (256 levels for each color). This makes 256*256*256=16777216 possible colors!
A HEX color is specified with an RGB (Red Green Blue) triplet in hexadecimal format.
A hexadecimal color is specified with: #RRGGBB.
RR (red), GG (green) and BB (blue) are hexadecimal integers between 00 and FF (Equivalent to 0 to 255 depending of the intensity of the color).