BOSONS
At the quantum level, each force of nature is transmitted by a dedicated particle or set of particles.

Electric charge: 0
Mass: 0
Carrier of electromagnetism, the quantum of light acts on electrically charged particles. It acts over unlimited distances.

Electric charge: 0
Mass: 91 MeV
Mediator of weak reactions that do not change the identity of particles. Its range is only about 10^-18 meter.

Electric charge: +1 or -1
Mass: 80.4 GeV
Mediators of weak reactions that change particle flavor and charge. Their range is only about 10^-18 meter.

Electric charge: 0
Mass: 0
Eight species of gluons carry the strong interaction, acting on quarks and on other gluons. They do not feel electromagnetic or weak interactions.

Electric charge: 0
Mass: Expected below 1 TeV, most likely between 113 and 192 GeV.
Believed to endow W and Z bosons, quarks and leptons with mass.

HOW THE FORCES ACT
An interaction among several colliding particles can change their energy, momentum or type. An interaction can even cause a single particle in isolation to decay spontaneously.

ELECTROMAGNETIC INTERACTION
The electromagnetic interaction acts on charged particles, leaving the particles unchanged. It causes like-charged particles to repel.

STRONG INTERACTION
The strong force acts on quarks and gluons. It binds them together to form protons, neutrons and more. Indirectly, it also binds protons and neutrons into atomic nuceli.

WEAK INTERACTION
The weak interaction acts on quarks and leptons. Its best-known effect is to transmute a down quark into an up quark, which in turn causes a neutron to become a proton plus an electron and a neutrino.

HIGGS INTERACTION
The Higgs field (gray background) is thought to fill space like a fluid, impeding the W and Z bosons and thereby limiting the range of weak interactions. The Higgs also interacts with quarks and leptons, endowing them with mass.