The primaries provide the main forward thrust for flight. On the wing, these are the feathers most distal (located nearest to the tip; furthest from the center of the body). Also called beam feathers in the UK, flight feathers or phalangeal feathers.
The components of a color in a color model. They may be actual primary colors perceivable by humans, as in RGB or CMYK, or they may be imaginary mathematical constructs, as with CIE XYZ (1931) or CIELAB.