A boson is the any particle with a spin that is an integer number (0, 1, 2, ...) of quantum units of angular momentum. Bosons, named by Paul Dirac in 1947 after the Indian physicist Satyendra Nath Bose, are the carrier particles of all fundamental interactions. Photons, the carrier of the electromagnetic force, for example, are bosons with spin 1. The as-yet-undetected graviton, associated with the gravitational force between masses, is expected toe have spin 2.
Bosons do not obey the Pauli exclusion principle. This means there is no limit to the number of bosons that can occupy the same point in space at the same time; so, for example, there is no limit in theory to the brightness of a beam of light. Compare with fermion.