Quarks are the things that make up protons and neutrons. There are more than two kinds of quarks, so they aren't classified as positive and negative, but in colours. They're classified red, green and blue, and their opposite colours. There are particles other than protons and neutrons that are made up of quarks, but these have a lifetime of fractions of a second. A particle can be made up of all three prime-coloured quarks or just a prime-colour and it's opposite colour. Protons and neutrons are made up of three quarks.
That's what my physics book says, anyway
(also, something might have been lost in the translation.)
