Bosons are elementary particles that "carry" things called fundamental interactions. fundamental interactions are the most basic categories of things that affect matter. There are 4 of these: gravity, a force that attracts matter to other matter; electromagnetism, the interaction of electric and magnetic fields; the strong nuclear force, a force that bonds quarks together to form larger particles; and the weak nuclear force, which can change the flavor of quarks and is involved in hadron decay. Photons carry the electromagnetic force, gluons carry the strong nuclear force, and w and z bosons carry the weak nuclear force. Although it is speculated that a theoretical particle called the graviton carries gravity, this has yet to be proven.