nimblermortal asked: What is the colour of a quark? Is it the same thing as its flavour?
Colour is really just something physicists came up with to describe and catergorise quarks.
Quarks are actually smaller than the wavelength of visible light so they do not have a colour in the traditional sense.
The flavours of quark are Up, Down, Strange, Charm, Top, and Bottom (or Beauty I think originally) and these names describe differences in charge and mass (Top being the heaviest, Up the lightest) and that’s all very well as far as classification goes.
But we needed something that would take into account the peculiar behaviour of quarks. Namely, that they only exist in certain combinations. Groups of three, or pairs of quark and antiquark. So the concept of colour was borrowed because you have red, green, and blue (RGB) combining to make white light. An anology we can see in practice easily.
And also the idea of complementary colours. Pairs of colour that will also form white when combined. The quark and its antiquark have complementary colour. Green and anti-green (here, magenta), etc.
So quarks can only exist together in a state of colour neutrality - whiteness. Or in the case of paints, blackness. And colour is just a handy way of describing that in an intuitive way to budding physicists.