It is common knowledge that Red, Yellow and Blue are the three primary colors, but there are actually three sets of Primary colors you should be familiar with.
What is a color?
Color:#FFFFFF
Color:#000000
White is the presence of all colors present in visible light. Black is the absence of any light or color. From these absolutes exist all colors in-between, and likewise we get two interfasted types of coloration, Additive and Subtractive Color
Are the Primary colors not just Red, Blue and Yellow?
Classic Primary: Red, Yellow, Blue
RYB (Red, Yellow, and Blue) is considered the classical set of primary colors. It's the first set of primary colors most people learn.
The classical primary color wheel is a Subtractive Color set. This means all of the pigments come together to create black.
In practice, The classic Subtractive Color set is considered a less scientifically disciplined set of primary colors compared to the modern Subtractive sets, and likewise it is not used often in modern color production.
That does not mean it lacks utility. The Classical Primary color wheel is still widely held as standard for creating color schemes with Color Theory: a set of rules for creating appealing and cohesive color schemes.
So what colors are being used now?
Subtractive Primary: Cyan, Magenta, Yellow
The Modern Subtractive Primary colors are Cyan, Magenta, Yellow (CMY). This set of colors is the current standard for most printing and pigments.
While all of the pigments in CMY come together to create black, more often than not Black (K) is added as its own pigment as it is more efficient and effective to use a singular black pigment than to layer all the other pigments.
Some examples of subtractive color in application:
So theres a second type of primary colors?
The Additive Primary colors are Red, Green, and Blue (RGB). Additive colors are usualy colored light aposed to being pigmets.
Additive Primary: Red, Green, Blue
Unlike subtractive coloring where layering or mixing colors results in a darker sum, Additive colors layer together to create white. Likewise Additive colors are mostly used for colored lighting and electronic displays.
Some examples of additive color in application:
The secondary colors of The additive and modern subtractive color wheels are the primary colors of the opposite wheel. It is not a coincidence that both sets reflect eachother and are workable with the full spectum of colored light.
The classical subtractive Primaries, however, have a unique set of Secondary colors. Green, Purple, and Orange.