All matter in the world around us consists of atoms. All atoms consist of electrons, which interact with a nucleus consisting of quarks. In ordinary matter the quarks interact with each other in such a way, that they form the compound bodies neutrons and protons. As seen from the figure above, all the various appearances of matter around us are composed of just three kind of “elementary particles” - electrons, up-quarks and down-quarks. However, in high-energy laboratories, in the interior of stars and at the beginning of this universe, other species of “elementary particles” are encountered.
The interactions between the atomic electrons and the nucleus, as a whole, is the domain of atomic physics while the internal affairs of the nucleus is the domain of nuclear physics. Thus, these two sciences are concerned with the first few steps in the construction of all the material objects we see around us. “Particle” physics, on the other hand, is concerned with what happens on a much smaller scale - about 10-100 million times smaller than the size of an atom. The domain of this branch of physics is the creation and behavior of “elementary particles” - which may combine to form atoms or may not combine to form anything at all.
The electrons belong to the class of “elementary particles” called leptons. The leptons and the quarks together constitute the class called fermions. According to the Standard Model all matter is constituted by fermions. Whether the fermions combine to form a table, a star, a human body, a flower or do not combine at all depend on the four elementary forces - the electromagnetic, the gravitational, the weak and the strong forces.
According to the Standard Model all force is mediated by exchange of (gauge) bosons. The electromagnetic force is mediated by exchange of photons, the strong force by exchange of gluons while the weak force is mediated by exchange of W and Z bosons. The gravitational force is special in the sense that, on the levels currently pondered by quantum physicists, it is too insignificant to even be considered.
The whole set of presently detected “elementary particles” is listed in the tables above. However, each quark comes in three slightly different variants (three colors), the gluon comes in eight variants and all fermions have an “antiparticle” of the same mass but of opposite charge.