What Is the RGB Color Model?
RGB (Red, Green, Blue) is an additive color model in which light of three primary colors is combined to create a full visible spectrum. It is the color model used by all digital displays — monitors, phones, TVs — where colors are produced by illuminating tiny red, green, and blue subpixels at varying intensities.
How RGB Values Work
Each channel (R, G, B) ranges from 0 to 255 (8 bits). 0 means no contribution; 255 means full intensity. rgb(255, 0, 0) is pure red; rgb(0, 255, 0) is pure green; rgb(0, 0, 255) is pure blue. rgb(255, 255, 255) is white (all channels full); rgb(0, 0, 0) is black (all off). rgb(128, 128, 128) is medium gray.
RGB vs CMYK
RGB is additive — mixing all three primaries at full intensity produces white light. CMYK (Cyan, Magenta, Yellow, Key/Black) is subtractive — mixing all pigments produces black. Screens use RGB; printers use CMYK. Colors look different across media because of this fundamental difference. Design files need RGB-to-CMYK conversion before commercial printing.
HEX and RGB
CSS hex colors (#RRGGBB) and rgb() notation are equivalent representations. #FF5733 = rgb(255, 87, 51) — convert each pair of hex digits from base-16 to decimal: FF=255, 57=87, 33=51. 3-digit hex (#RGB) is shorthand: each digit is doubled, so #F53 = #FF5533 = rgb(255, 85, 51). All three notations describe exactly the same color.
HSL and HSB: Alternative Color Spaces
HSL (Hue, Saturation, Lightness) and HSB/HSV (Hue, Saturation, Brightness/Value) are cylindrical color spaces more intuitive for designers. Hue is measured in degrees (0°=red, 120°=green, 240°=blue). Saturation is the color purity. Lightness/Brightness controls overall tone. Adjusting only lightness keeps the color the same — useful for creating button hover states and tints.