[Jack]

I can't pretend to understand all this, but I can Google:

In particle physics, the quark (pronounced IPA: /kwɔː(r)k/) is one of the two basic constituents of matter (the other is the lepton). It is quarks that make up protons and neutrons, with there being exactly three quarks within each kind of particle. There are six different types of quark, usually known as flavors: up, down, charm, strange, top, and bottom. (Their names were chosen arbitrarily based on the need to name them something that could be easily remembered and used.) The strange, charm, bottom and top varieties are highly unstable and died out within a fraction of a second after the Big Bang; they can be recreated and studied by particle physicists. The up and down varieties survive in profusion, and are distinguished by (among other things) their electric charge. It is this which makes the difference when quarks clump together to form protons or neutrons: a proton is made up of two up quarks and one down quark, yielding a net charge of +1; while a neutron contains one up quark and two down quarks, yielding a net charge of 0. Quarks are the only fundamental particles that interact through all four of the fundamental forces. Antiparticles of quarks are called antiquarks. Isolated quarks are never found naturally; they are almost always found in groups of two (mesons) or groups of three (baryons) called hadrons. This is a direct consequence of confinement.

Quark - Wikipedia, the free encyclopedia