11.2.1—A quark is a fundamental particle and that there are six flavours (types) of

The six quark flavours are up, down, strange, charm, top and bottom. Quarks are treated as fundamental constituents of hadrons in the standard model.

Use the flavour names as a classification and distinguish quarks from composite protons and neutrons.

Ordinary nuclear matter is mainly built from up and down quarks, while strange, charm, top and bottom appear in higher-energy or unstable particles.

A quark is not a smaller proton; hadrons are composite states made from quarks.