[hvindin]

Both of those statements are correct in context.

RGB if a thing is emitting light.

CMYK if a thing is reflecting light.

So it is true to say "Red, green, and blue are the basic building blocks of other colours"

It is also true to say "When you were told in primary school that the primary colours for your paints were red, green, and blue, this was untrue"

I do actually think that this is an example of a somewhat muddled thought process that is jumping from one thing to a other pretty eratically, or perhaps of something being edited such that it is now confusing to a reader going over it for the first time, honestly the whole thing reads a little like it was written by someone who really enjoys stimulants and can't keep their focus on one thing. But _technically_ I don't think any of the content is _wrong_ (obviously this means excluding ~70% of the content because it's largely about how people feel, and this is probably never _wrong_ but it's also not a matter of fact...)

[hvindin]

No, actually, my bad, I went back and read that bit over again for a third time and it does actually say red yellow blue aren't primary, but that the primary colours are red yellow and blue.

You were correct and I jusy managed to misread the article twice....

[weinzierl]

> It is also true to say "When you were told in primary school that the primary colours for your paints were red, green, and blue, this was untrue"

The reason that red, green and blue are sometimes stated as primary colors in the context of mixing ink layers is that red and green and blue are rather vague terms. What is meant by red in this context would more exactly be called magenta and green is used to designate cyan. Wikipedia puts it this way[1]:

> Before the color names cyan and magenta were in common use, these primaries were often known as blue and red, respectively, and their exact color has changed over time with access to new pigments and technologies.

Also I think education about primary colors is just a mess and the same Wikipedia article[1] talks about this too:

> Elementary art education materials, dictionaries, and electronic search engines often define primary colors effectively as conceptual colors (generally magenta, yellow, and cyan; or red, green, and blue) that can be used to mix "all" other colors and often go further and suggest that these conceptual colors correspond to specific hues and precise wavelengths. Such sources do not present a coherent, consistent definition of primary colors since real primaries cannot be complete.

[1] https://en.wikipedia.org/wiki/Primary_color