What is a boson, as described by the standard model?

A boson is a "force-carrier": a particle that corresponds to one of the fundamental forces of nature. There are four fundamental forces, which include: Gravity, Electromagnetism, Weak Nuclear Force and Strong Nuclear Force.For example, the photon is the force-carrier (boson) for the electromagnetic force. Bosons act as a transmitter for their force onto particles of matter, e.g. the photon is what causes charged particles to be affected by an electric or magnetic field.