Is black the presence of all colors and white the absence of all colors?

Other way around.

That’s what I heard. It seems counter intuitive to me.

Well, the color of an object is the color it reflects. Blue things look blue because they absorb every other wavelength of light except blue. The blue wavelengths get reflected, hit our eyeballs, and we see blue.

Like you said, black absorbs and white reflects. So white is the reflection of all wavelengths of light. Black is the absorption of all wavelengths.

For pigments, mixing all colors gives you black.

For light, mixing all colors gives you white.

(Pigments reduce reflected light. It makes sense.)

Right! I forgot about that part @Mariah, the color it is is the color that it actually isn’t!

For light, white=all colours and black= no colours, andfor paint mixing, the other way around.