From the Wikipedia page on the RGB color model -> Numeric representations:
A color in the RGB color model is described by indicating how much of each of the red, green, and blue is included. The color is expressed as an RGB triplet (r,g,b), each component of which can vary from zero to a defined maximum value. If all the components are at zero the result is black; if all are at maximum, the result is the brightest representable white.
What exactly is each step in one channel/color? What does it increase? Luma? Intensity? Saturation? Chroma? Chrominance?