There are six quarks, but physicists usually talk about the three pairs of quarks: Up/Down, Charm/Strange, and Top/Bottom. For each of these quarks there is a corresponding antimatter-quark (anti-quark.)

Quarks have the unusual characteristic of having fractional electric charge of either 2/3 or -1/3, unlike the -1 charge of an electron and the +1 charge of the proton. Quarks also carry another type of charge called color charge, which we will discuss later.

Quarks are interesting particles. There is a funny story about the discovery of and naming of quarks. Perhaps the most famous quark, the long sought-after top quark, was recently discovered. For your entertainment, would you like to see a cork model?